WorldWideScience

Sample records for hydrogen desorption properties

  1. Study on hydrogen absorption/desorption properties of uranium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroshi; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    Hydrogen absorption/desorption properties of two U-Mn intermetallic compounds, U{sub 6}Mn and UMn{sub 2}, were investigated. U{sub 6}Mn absorbed hydrogen and the hydrogen desorption pressure of U{sub 6}Mn obtained from this experiment was higher than that of U, which was considered to be the effect of alloying, whereas UMn{sub 2} was not observed to absorb hydrogen up to 50 atm at room temperature. (author)

  2. Enhanced hydrogen desorption property of MgH{sub 2} with the addition of cerium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huai-Jun, E-mail: huaijun.lin.489@s.kyushu-u.ac.jp [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Matsuda, Junko [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Li, Hai-Wen [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan); Zhu, Min [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); China–Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510640 (China); Akiba, Etsuo [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-05

    Highlights: • Activation energy of MgH{sub 2} desorption is remarkably reduced with the dopant of CeF{sub 4}. • The improvement might be attributed to new Ce–F–Mg species at the CeF{sub 4}/MgH{sub 2} interface. • Easy electron transfer induced from the high valence Ce-cation benefits MgH{sub 2} desorption. - Abstract: Hydrogen desorption property of MgH{sub 2} doped with cerium fluorides with different valences prepared using ball milling has been studied. CeF{sub 4} is catalytically active for hydrogen desorption of MgH{sub 2}. Hydrogen desorption temperature and apparent activation energy of MgH{sub 2} are significantly reduced with dopant of 2 mol% of CeF{sub 4}, which might be attributed to the formation of a new Ce–F–Mg specie at the CeF{sub 4}/MgH{sub 2} interface and the easy electron transfer induced from the high valence Ce-cation. The apparent activation energy of hydrogen desorption of MgH{sub 2} is reduced from ∼160 kJ/mol to ∼110 kJ/mol with the dopant of CeF{sub 4}.

  3. Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy

    CERN Document Server

    Shuai Mao Bing; WangZhenHong; Zhang Yi Tao

    2001-01-01

    Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy are investigated in detail at hydrogen pressures up to 0.4 MPa and over the temperature range of 300 to 723 K. It absorbs hydrogen up to 2.3 H atoms per F.U. (formula unit) by only one-step reaction and hence each desorption isotherm has a single plateau over nearly the whole hydrogen composition range. The enthalpy and entropy changes of the dissociation reaction are of -78.9 kJ centre dot mol sup - sup 1 H sub 2 and 205.3 J centre dot(K centre dot mol H sub 2) sup - sup 1 , respectively. The alloy shows high durability against powdering upon hydrogenation and may have good heat conductivity. It is predicted that UZr sub 0 sub . sub 2 sub 9 alloy may be a suitable material for tritium treatment and storage

  4. Changes of structural and hydrogen desorption properties of MgH2 indused by ion irradiation

    Directory of Open Access Journals (Sweden)

    Kurko Sandra V.

    2010-01-01

    Full Text Available Changes in structural and hydrogen desorption properties of MgH2 induced by ion irradiation have been investigated. MgH2 powder samples have been irradiated with 45 keV B3+ and 120 keV Ar8+ions, with ion fluence of 1015 ions/cm2. The effects of ion irradiation are estimated by numerical calculations using SRIM package. The induced material modifications and their consequences on hydrogen dynamics in the system are investigated by XRD, particle size distribution and TPD techniques. Changes of TPD spectra with irradiation conditions suggest that there are several mechanisms involved in desorption process which depend on defect concentration and their interaction and ordering. The results confirmed that the near-surface area of MgH2 and formation of a substoichiometric MgHx (x<2 play a crucial role in hydrogen kinetics and that various concentrations of induced defects substantially influence H diffusion and desorption kinetics in MgH2. The results also confirm that there is possibility to control the thermodynamic parameters by controlling vacancies concentration in the system.

  5. Hydrogen Desorption Properties of Bulk and Nanoconfined LiBH4-NaAlH4

    Directory of Open Access Journals (Sweden)

    Payam Javadian

    2016-06-01

    Full Text Available Nanoconfinement of 2LiBH4-NaAlH4 into a mesoporous carbon aerogel scaffold with a pore size, BET surface area and total pore volume of Dmax = 30 nm, SBET = 689 m2/g and Vtot = 1.21 mL/g, respectively is investigated. Nanoconfinement of 2LiBH4-NaAlH4 facilitates a reduction in the temperature of the hydrogen release by 132 °C, compared to that of bulk 2LiBH4-NaAlH4 and the onset of hydrogen release is below 100 °C. The reversible hydrogen storage capacity is also significantly improved for the nanoconfined sample, maintaining 83% of the initial hydrogen content after three cycles compared to 47% for that of the bulk sample. During nanoconfinement, LiBH4 and NaAlH4 reacts to form LiAlH4 and NaBH4 and the final dehydrogenation products, obtained at 481 °C are LiH, LiAl, AlB2 and Al. After rehydrogenation of the nanoconfined sample at T = 400 °C and p(H2 = 126 bar, amorphous NaBH4 is recovered along with unreacted LiH, AlB2 and Al and suggests that NaBH4 is the main compound that can reversibly release and uptake hydrogen.

  6. High hydrogen desorption properties of Mg-based nanocomposite at moderate temperatures: The effects of multiple catalysts in situ formed by adding nickel sulfides/graphene

    Science.gov (United States)

    Xie, Xiubo; Chen, Ming; Liu, Peng; Shang, Jiaxiang; Liu, Tong

    2017-12-01

    Nickel sulfides decorated reduced graphene oxide (rGO) has been produced by co-reducing Ni2+ and graphene oxide (GO), and is subsequently ball milled with Mg nanoparticles (NPs) produced by hydrogen plasma metal reaction (HPMR). The nickel sulfides of about 800 nm completely in situ change to MgS, Mg2Ni and Ni multiple catalysts after first hydrogenation/dehydrogenation process at 673 K. The Mg-5wt%NiS/rGO nanocomposite shows the highest hydrogen desorption kinetics and capacity properties, and the catalytic effect order of the additives is NiS/rGO, NiS and rGO. At 573 K, the Mg-NiS/rGO nanocomposite can quickly desorb 3.7 wt% H2 in 10 min and 4.5 wt% H2 in 60 min. The apparent hydrogen absorption and desorption activation energies of the Mg-5wt%NiS/rGO nanocomposite are decreased to 44.47 and 63.02 kJ mol-1, smaller than those of the Mg-5wt%rGO and Mg-5wt%NiS samples. The best hydrogen desorption properties of the Mg-5wt%NiS/rGO nanocomposite can be explained by the synergistic catalytic effects of the highly dispersed MgS, Mg2Ni and Ni catalysts on the rGO sheets, and the more nucleation sites between the catalysts, rGO sheets and Mg matrix.

  7. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  8. Hydrogen storage properties on mechanically milled graphite

    OpenAIRE

    Ichikawa, Takayuki; Chen, D. M.; Isobe, Shigehito; Gomibuchi, Emi; Fujii, Hironobu

    2004-01-01

    We investigated hydrogen absorption/desorption and structural properties in mechanically milled graphite under hydrogen pressures up to 6 MPa to clarify catalytic and hydrogen pressure effects in the milling. The results indicate that a small amount of iron contamination during milling plays a quite important role as a catalyst for hydrogen absorption/desorption properties in graphite. Two-peak structure for hydrogen desorption in the TDS profile is due to existence of two different occupatio...

  9. HYDROGEN AND ITS DESORPTION IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    HSEUH,H.C.

    2002-11-11

    Hydrogen is the dominating gas specie in room temperature, ultrahigh vacuum systems of particle accelerators and storage rings, such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven. Rapid pressure increase of a few decades in hydrogen and other residual gases was observed during RHIC's recent high intensity gold and proton runs. The type and magnitude of the pressure increase were analyzed and compared with vacuum conditioning, beam intensity, number of bunches and bunch spacing. Most of these pressure increases were found to be consistent with those induced by beam loss and/or electron stimulated desorption from electron multipacting.

  10. Hydrogen Desorption Properties of Nanocrystalline MgH2-10 wt.% ZrB2 Composite Prepared by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    Mona Maddah

    2014-06-01

    Full Text Available Storage of hydrogen is one of the key challenges in developing hydrogen economy. Magnesium hydride (MgH2 is an attractive candidate for solid-state hydrogen storage for on-board applications. In this study, 10 wt.% ZrB2 was co-milled with magnesium hydride at different milling times to produce nanocrystalline composite powder. The effect of milling time and additive on the hydrogen desorption properties of obtained powder was evaluated by thermal analyzer method and compared with pure MgH2. The phase constituents of powder particles were characterized by X-ray diffractometry method. The grain size and lattice strain of β-MgH2 phase were estimated from the broadening of XRD peaks using Williamson–Hall method. The size and morphological changes of powder particles upon mechanical alloying were studied by scanning electron microscopy. XRD analysis showed that the mechanically activated magnesium hydride consisted of β-MgH2, γ-MgH2 and small amount of MgO. It is shown that the addition of ZrB2 to magnesium hydride yields a finer particle size. The thermal analyses results showed that the addition of ZrB2 particle to magnesium hydride and mechanical alloying for 30 h reduced the dehydrogenation temperature of magnesium hydride from 319 °C to 308 °C. This can be attributed to the particle size reduction of magnesium hydride.

  11. The synergistic effect of catalysts on hydrogen desorption properties of MgH2–TiO2–NiO nanocomposite

    Directory of Open Access Journals (Sweden)

    Farshad Rajabpour

    2016-10-01

    Full Text Available Abstract The high desorption temperature and slow desorption kinetics of MgH2 makes it less competitive for future mobile applications; using a catalyst accompanied by mechanical milling seems to be a good solution to overcome those problems. Therefore, the addition of TiO2 and NiO to MgH2 accompanied by 15 h of mechanical milling was considered in this study. The phase constituent and hydrogen desorption of the powder mixture were investigated using X-ray diffraction (XRD and a Sievert-type apparatus, respectively. XRD results showed that after milling, no binary or ternary compounds were formed, but hydrogen desorption time decreased and the desorbed hydrogen content increased. It seems that the increase in desorbed hydrogen was related to the simultaneous catalytic effect of TiO2 and NiO as well as mechanical milling. The results showed that the addition of both catalysts can improve the hydrogen desorption behavior of MgH2-based nanocomposite compared to the addition of only one catalyst of the same amount.

  12. Hydrogen sorption and desorption properties of Pd-alloys and steels investigated by electrochemical methods and mass spectrometry

    NARCIS (Netherlands)

    Uluc, A.V.

    2015-01-01

    Although it has been more than a century since the first known hydrogen embrittlement case was reported, the fundamental question regarding its mechanism is still open to debate. Understanding the hydrogen-metal interactions is of great importance in tailoring microstructures that will have

  13. Current-Driven Hydrogen Desorption from Graphene: Experiment and Theory

    Energy Technology Data Exchange (ETDEWEB)

    Gao, L.; Pal, Partha P.; Seideman, Tamar; Guisinger, Nathan P.; Guest, Jeffrey R.

    2016-02-04

    Electron-stimulated desorption of hydrogen from the graphene/SiC(0001) surface at room temperature was investigated with ultrahigh vacuum scanning tunneling microscopy and ab initio calculations in order to elucidate the desorption mechanisms and pathways. Two different desorption processes were observed. In the high electron energy regime (4-8 eV), the desorption yield is independent of both voltage and current, which is attributed to the direct electronic excitation of the C-H bond. In the low electron energy regime (2-4 eV), however, the desorption yield exhibits a threshold dependence on voltage, which is explained by the vibrational excitation of the C-H bond via transient ionization induced by inelastic tunneling electrons. The observed current-independence of the desorption yield suggests that the vibrational excitation is a singleelectron process. We also observed that the curvature of graphene dramatically affects hydrogen desorption. Desorption from concave regions was measured to be much more probable than desorption from convex regions in the low electron energy regime (~ 2 eV), as would be expected from the identified desorption mechanism

  14. Electric field dependent structural and vibrational properties of the Si(100)-H(2 x 1) surface and its implications for STM induced hydrogen desorption

    DEFF Research Database (Denmark)

    Stokbro, Kurt

    1999-01-01

    We report a first principles study of the structure and the vibrational properties of the Si(100)-H(2 x 1) surface in an electric field. The calculated vibrational parameters are used to model the vibrational modes in the presence of the electric field corresponding to a realistic scanning...... at room temperature). We calculate the implications for current induced desorption of H using a recently developed first principles model of electron inelastic scattering. The calculations show that inelastic scattering events with energy transfer n (h) over bar omega, where n>1, play an important role...

  15. Adsorption and desorption of hydrogen at nonpolar GaN (1 1 ¯ 00 ) surfaces: Kinetics and impact on surface vibrational and electronic properties

    Science.gov (United States)

    Lymperakis, L.; Neugebauer, J.; Himmerlich, M.; Krischok, S.; Rink, M.; Kröger, J.; Polyakov, V. M.

    2017-05-01

    The adsorption of hydrogen at nonpolar GaN (1 1 ¯00 ) surfaces and its impact on the electronic and vibrational properties is investigated using surface electron spectroscopy in combination with density functional theory (DFT) calculations. For the surface mediated dissociation of H2 and the subsequent adsorption of H, an energy barrier of 0.55 eV has to be overcome. The calculated kinetic surface phase diagram indicates that the reaction is kinetically hindered at low pressures and low temperatures. At higher temperatures ab initio thermodynamics show, that the H-free surface is energetically favored. To validate these theoretical predictions experiments at room temperature and under ultrahigh vacuum conditions were performed. They reveal that molecular hydrogen does not dissociatively adsorb at the GaN (1 1 ¯00 ) surface. Only activated atomic hydrogen atoms attach to the surface. At temperatures above 820 K, the attached hydrogen gets desorbed. The adsorbed hydrogen atoms saturate the dangling bonds of the gallium and nitrogen surface atoms and result in an inversion of the Ga-N surface dimer buckling. The signatures of the Ga-H and N-H vibrational modes on the H-covered surface have experimentally been identified and are in good agreement with the DFT calculations of the surface phonon modes. Both theory and experiment show that H adsorption results in a removal of occupied and unoccupied intragap electron states of the clean GaN (1 1 ¯00 ) surface and a reduction of the surface upward band bending by 0.4 eV. The latter mechanism largely reduces surface electron depletion.

  16. Effect of oxygen on the hydrogenation properties of magnesium films

    DEFF Research Database (Denmark)

    Ostenfeld, Christopher Worsøe; Chorkendorff, Ib

    2006-01-01

    The effect of magnesium oxide on the magnesium and hydrogen desorption properties of magnesium films have been investigated. We find that by capping metallic magnesium films with oxide overlayers the apparent desorption energy of magnesium is increased from 146 kJ/mol to 314 kJ/mol. The results...... are discussed in light of previous investigations of ball-milled magnesium powders....

  17. Functional differential equations of neutral type with integrable weak singularity: hydrogen thermal desorption model

    Science.gov (United States)

    Zaika, Yury V.; Kostikova, Ekaterina K.

    2017-11-01

    One of the technological challenges for hydrogen materials science (including the ITER project) is the currently active search for structural materials with various potential applications that will have predetermined limits of hydrogen permeability. One of the experimental methods is thermal desorption spectrometry (TDS). A hydrogen-saturated sample is degassed under vacuum and monotone heating. The desorption flux is measured by mass spectrometer to determine the character of interactions of hydrogen isotopes with the solid. We are interested in such transfer parameters as the coefficients of diffusion, dissolution, desorption. The paper presents a thermal desorption functional differential equations of neutral type with integrable weak singularity and a numerical method for TDS spectrum simulation, where only integration of a nonlinear system of low order ordinary differential equations (ODE) is required. This work is supported by the Russian Foundation for Basic Research (project 15-01-00744).

  18. Modelling of hydrogen thermal desorption spectrum in nonlinear dynamical boundary-value problem

    Science.gov (United States)

    Kostikova, E. K.; Zaika, Yu V.

    2016-11-01

    One of the technological challenges for hydrogen materials science (including the ITER project) is the currently active search for structural materials with various potential applications that will have predetermined limits of hydrogen permeability. One of the experimental methods is thermal desorption spectrometry (TDS). A hydrogen-saturated sample is degassed under vacuum and monotone heating. The desorption flux is measured by mass spectrometer to determine the character of interactions of hydrogen isotopes with the solid. We are interested in such transfer parameters as the coefficients of diffusion, dissolution, desorption. The paper presents a distributed boundary-value problem of thermal desorption and a numerical method for TDS spectrum simulation, where only integration of a nonlinear system of low order (compared with, e.g., the method of lines) ordinary differential equations (ODE) is required. This work is supported by the Russian Foundation for Basic Research (project 15-01-00744).

  19. A study on metal organic framework (MOF-177) synthesis, characterization and hydrogen adsorption -desorption cycles

    Energy Technology Data Exchange (ETDEWEB)

    Viditha, V.; Venkateswer Rao, M.; Srilatha, K.; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad-500 085, A.P. (India); Yerramilli, Anjaneyulu [Director, TLGVRC, JSU Box 18739, JSU, Jackson, MS 32917-0939 (United States)

    2013-07-01

    Hydrogen has long been considered to be an ideal alternative to fossil-fuel systems and much work has now been done on its storage. There are four main methods of hydrogen storage: as a liquid; as compressed hydrogen; in the form of metal hydrides; and by physisorption. Among all the materials metal organic frameworks (MOFs) are considered to have desirable properties like high porosity, pore volume and high thermal stability. MOF-177 is considered to be an ideal storage material. In this paper we study about its synthesis and hydrogen storage capacities of MOF-177 at different pressures ranging from 25, 50, 75 and 100 bar respectively. The obtained samples are characterized by XRD, BET and SEM. The recorded results show that the obtained hydrogen capacity is 1.1, 2.20, 2.4 and 2.80 wt%. The desorption capacity is 0.9, 2.1, 2.37 and 2.7 wt% at certain temperatures like 373 K.

  20. Measurements of hydrogen content in bulk niobium by Thermal Desorption Spectroscopy

    CERN Document Server

    Hakovirta, M

    2001-01-01

    The hydrogen content of bulk niobium has been studied by Thermal Desorption Spectroscopy. The work has been focussed initially on the influence of the vacuum firing and the surface chemical treatment. It is planned to extend the investigation to niobium samples of different quality and origin to ascertain the interest of using the Thermal Desorption Spectroscopy technique to qualify the raw niobium sheets to be used for cavity manufacturing

  1. Studies of hydrogen absorption and desorption processes in advanced intermetallic hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Masashi

    2005-07-01

    This work is a part of the research program performed in the Department of Energy Systems, Institute for Energy Technology (Kjeller, Norway), which is focused on the development of the advanced hydrogen storage materials. The activities are aimed on studies of the mechanisms of hydrogen interactions with intermetallic alloys with focus on establishing an interrelation between the crystal structure, thermodynamics and kinetics of the processes in the metal-hydrogen systems, on the one hand, and hydrogen storage properties (capacity, rates of desorption, hysteresis). Many of the materials under investigation have potential to be applied in applications, whereas some already have been commercialised in the world market. A number of metals take up considerable amounts of hydrogen and form chemical compounds with H, metal hydrides. Unfortunately, binary hydrides are either very stable (e.g. for the rare earth metals [RE], Zr, Ti, Mg: metal R) or are formed at very high applied pressures of hydrogen gas (e.g. for the transition metals, Ni, Co, Fe, etc.: Metal T). However, hydrogenation process becomes easily reversible at very convenient from practical point of view conditions, around room temperature and at H2 pressures below 1 MPa for the two-component intermetallic alloys R{sub x}T{sub y}. This raised and maintains further interest to the intermetallic hydrides as solid H storage materials. Materials science research of this thesis is focused on studies of the reasons staying behind the beneficial effect of two non-transition elements M(i.e., In and Sn) contributing to the formation of the ternary intermetallic alloys R{sub x}T{sub y}M{sub 2}., on the hydrogen storage behaviours. Particular focus is on two aspects where the remarkable improvement of ordinary metal hydrides is achieved via introduction of In and Sn: a) Increase of the volume density of stored hydrogen in solid materials to the record high level. b) Improvement of the kinetics of hydrogen charge and

  2. Reactive Desorption of CO Hydrogenation Products under Cold Pre-stellar Core Conditions

    Science.gov (United States)

    Chuang, K.-J.; Fedoseev, G.; Qasim, D.; Ioppolo, S.; van Dishoeck, E. F.; Linnartz, H.

    2018-02-01

    The astronomical gas-phase detection of simple species and small organic molecules in cold pre-stellar cores, with abundances as high as ∼10‑8–10‑9 n H, contradicts the generally accepted idea that at 10 K, such species should be fully frozen out on grain surfaces. A physical or chemical mechanism that results in a net transfer from solid-state species into the gas phase offers a possible explanation. Reactive desorption, i.e., desorption following the exothermic formation of a species, is one of the options that has been proposed. In astronomical models, the fraction of molecules desorbed through this process is handled as a free parameter, as experimental studies quantifying the impact of exothermicity on desorption efficiencies are largely lacking. In this work, we present a detailed laboratory study with the goal of deriving an upper limit for the reactive desorption efficiency of species involved in the CO–H2CO–CH3OH solid-state hydrogenation reaction chain. The limit for the overall reactive desorption fraction is derived by precisely investigating the solid-state elemental carbon budget, using reflection absorption infrared spectroscopy and the calibrated solid-state band-strength values for CO, H2CO and CH3OH. We find that for temperatures in the range of 10 to 14 K, an upper limit of 0.24 ± 0.02 for the overall elemental carbon loss upon CO conversion into CH3OH. This corresponds with an effective reaction desorption fraction of ≤0.07 per hydrogenation step, or ≤0.02 per H-atom induced reaction, assuming that H-atom addition and abstraction reactions equally contribute to the overall reactive desorption fraction along the hydrogenation sequence. The astronomical relevance of this finding is discussed.

  3. Desorption of cryogenic layers of the solid hydrogens by electron bombardment

    DEFF Research Database (Denmark)

    Schou, Jørgen; Tratnik, Herbert; Thestrup Nielsen, Birgitte

    2008-01-01

    For solid hydrogenic films in the thickness range from similar to 50 ML to similar to 500 ML the desorption yield falls off inversely proportional to the thickness for both H-2 and D-2 films. This behavior is common for data obtained at CERN for solid H-2 and at Riso National Laboratory for solid...

  4. Hydrogen absorption/desorption characteristics of room temperature ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The present communication deals with the hydrogen storage characteristics of C15 laves phase. ZrMn2–xNix system tailored within the x values of 1\\25 to 1\\50. Drastic variations in thermodynamics of the hydride phase is observed for any little changes of concentration x within this narrow range. The most prom-.

  5. Hydrogen absorption/desorption characteristics of room temperature ...

    Indian Academy of Sciences (India)

    ... hydrogen storage materials are found to be formed within the range of 1.35 to 1.45 where ∼ 2.5 to 2.9 H/F.U. can be reversibly stored under the ideal operating conditions. The heat of the reaction is found to be ∼ 17 kJ/mol, which means these are promising candidates for stationary and short range mobile applications.

  6. Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

    Science.gov (United States)

    Li, Ming; Huang, Xiaobo; Kang, Zhan

    2015-08-01

    Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials.

  7. Finite-temperature hydrogen adsorption and desorption thermodynamics driven by soft vibration modes.

    Science.gov (United States)

    Woo, Sung-Jae; Lee, Eui-Sup; Yoon, Mina; Kim, Yong-Hyun

    2013-08-09

    It has been widely accepted that enhanced dihydrogen adsorption is required for room-temperature hydrogen storage on nanostructured porous materials. Here we report, based on results of first-principles total energy and vibrational spectrum calculations, finite-temperature adsorption and desorption thermodynamics of hydrogen molecules that are adsorbed on the metal center of metal-porphyrin-incorporated graphene. We have revealed that the room-temperature hydrogen storage is achievable not only with the enhanced adsorption enthalpy, but also with soft-mode driven vibrational entropy of the adsorbed dihydrogen molecule. The soft vibration modes mostly result from multiple orbital coupling between the hydrogen molecule and the buckled metal center, for example, in Ca-porphyrin-incorporated graphene. Our study suggests that the current design strategy for room-temperature hydrogen storage materials should be modified with explicitly taking the finite-temperature vibration thermodynamics into account.

  8. Improvement in hydrogen desorption from β- and γ-MgH2 upon transition-metal doping.

    Science.gov (United States)

    Hussain, Tanveer; Maark, Tuhina Adit; Chakraborty, Sudip; Ahuja, Rajeev

    2015-08-24

    A thorough study of the structural, electronic, and hydrogen-desorption properties of β- and γ-MgH2 phases substituted by selected transition metals (TMs) is performed through first-principles calculations based on density functional theory (DFT). The TMs considered herein include Sc, V, Fe, Co, Ni, Cu, Y, Zr, and Nb, which substitute for Mg at a doping concentration of 3.125 % in both the hydrides. This insertion of TMs causes a variation in the cell volumes of β- and γ-MgH2 . The majority of the TM dopants decrease the lattice constants, with Ni resulting in the largest reduction. From the formation-energy calculations, it is predicted that except for Cu and Ni, the mixing of all the selected TM dopants with the MgH2 phases is exothermic. The selected TMs also influence the stability of both β- and γ-MgH2 and cause destabilization by weakening the MgH bonds. Our results show that doping with certain TMs can facilitate desorption of hydrogen from β- and γ-MgH2 at much lower temperatures than from their pure forms. The hydrogen adsorption strengths are also studied by density-of-states analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Behavior of hydrogen atoms in boron films during H{sub 2} and He glow discharge and thermal desorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzuki, K.; Natsir, M.; Inoue, N. [and others

    1995-09-01

    Hydrogen absorption and desorption characteristics in boron films deposited on a graphite liner have been studied. Number of hydrogen atoms absorbed in the films is estimated from a decrease in hydrogen pressure during a hydrogen glow discharge. It was 1.9 x 10{sup 17} atoms/cm{sup 2} in the 1 hour discharge after an evacuation of H atoms contained in the original boron films by thermal desorption. Hydrogen atoms were absorbed continuously without saturation for 3 hours during the discharge. Number of H atoms absorbed reached to 2.6 x 10{sup 17} atoms/cm{sup 2} at 3 hour. A discharge in helium was carried out to investigate H desorption characteristics from hydrogen implanted boron films. It was verified that reactivity for hydrogen absorption was recovered after the He discharge. Hydrogen atoms were accumulated in the films by repetition of alternate He and H{sub 2} discharge. Thermal desorption experiments have been carried out by raising the liner temperature up to 500degC for films after 1 hour, 3 hours hydrogen discharge and 6 times repetition of H{sub 2}/He discharges. Most of H atoms in the films were desorbed for all these cases. The slow absorption process was confirmed through the thermal desorption experiments. (author).

  10. Effects and Mechanisms of Mechanical Activation on Hydrogen Sorption/ Desorption of Nanoscale Lithium Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Leon, L.; Yang, Gary, Z.; Crosby, Kyle; Wwan, Xufei. Zhong, Yang; Markmaitree, Tippawan; Osborn, William; Hu, Jianzhi; Kwak, Ja Hun

    2012-04-26

    The objective of this project is to investigate and develop novel, mechanically activated, nanoscale Li3N-based and LiBH4-based materials that are able to store and release {approx}10 wt% hydrogen at temperatures near 100 C with a plateau hydrogen pressure of less than 10 bar. Four (4) material systems have been investigated in the course of this project in order to achieve the project objective. These 4 systems are (i) LiNH2+LiH, (ii) LiNH2+MgH2, (iii) LiBH4, and (iv) LiBH4+MgH2. The key findings we have obtained from these 4 systems are summarized below. *The thermodynamic driving forces for LiNH2+LiH and LiBH4 systems are not adequate to enable H2 release at temperatures < 100 C. *Hydrogen release in the solid state for all of the four systems is controlled by diffusion, and thus is a slow process. *LiNH2+MgH2 and LiBH4+MgH2 systems, although possessing proper thermodynamic driving forces to allow for H2 release at temperatures < 100 C, have sluggish reaction kinetics because of their diffusion-controlled rate-limiting steps. *Reducing particles to the nanometer length scale (< 50 nm) can improve the thermodynamic driving force to enable H2 release at near ambient temperature, while simultaneously enhancing the reaction kinetics as well as changing the diffusion-controlled rate-limiting step to gas desorption-controlled rate-limiting step. This phenomenon has been demonstrated with LiBH4 and offers the hope that further work along this direction will make one of the material systems, i.e., LiBH4, LiBH4+MgH2 and LiNH2+MgH2, possess the desired thermodynamic properties and rapid H2 uptake/release kinetics for on-board applications. Many of the findings and knowledge gained from this project have been published in archival refereed journal articles [1-15] and are accessible by general public. Thus, to avoid a bulky final report, the key findings and knowledge gained from this project will be succinctly summarized, particularly for those findings and knowledge

  11. In situ detection of hydrogen retention in TEXTOR by laser induced desorption

    Energy Technology Data Exchange (ETDEWEB)

    Schweer, B., E-mail: B.Schweer@fz-juelich.d [Forschungszentrum Juelich GmbH, Institute of Energy Research, IEF-4 Plasma Physis, Association EURATOM-FZJ, Trilateral Euregio Cluster, 52425 Juelich (Germany); Irrek, F.; Zlobinski, M.; Huber, A.; Sergienko, G.; Brezinsek, S.; Philipps, V.; Samm, U. [Forschungszentrum Juelich GmbH, Institute of Energy Research, IEF-4 Plasma Physis, Association EURATOM-FZJ, Trilateral Euregio Cluster, 52425 Juelich (Germany)

    2009-06-15

    Long term tritium retention is one of the most critical issues for ITER and future fusion devices. While a global analysis of the T retention can be made by T accountancy in the activated phase of ITER, fuel retention and control must be already addressed in the non- activated phase, to identify the mechanism, location and amount of retention, its dependence on plasma and wall conditions and to qualify T retention mitigation and control techniques. For this purpose a new diagnostic, laser induced desorption spectroscopy of retained fuel has been developed and applied in TEXTOR. Hydrogen isotopes are desorbed from re-deposited layers on graphite plates by rapid heating with laser radiation. The released particles have been quantified in situ by spectroscopic measurements of hydrogen lines in a tokamak plasma. The results were validated by ex situ analysis of the hydrogen content of deposited a-C:H layers.

  12. Sticking and desorption of hydrogen on graphite: A comparative study of different models

    Science.gov (United States)

    Lepetit, Bruno; Lemoine, Didier; Medina, Zuleika; Jackson, Bret

    2011-03-01

    We study the physisorption of atomic hydrogen on graphitic surfaces with four different quantum mechanical methods: perturbation and effective Hamiltonian theories, close coupling wavepacket, and reduced density matrix propagation methods. Corrugation is included in the modeling of the surface. Sticking is a fast process which is well described by all methods. Sticking probabilities are of the order of a few percent in the collision energy range 0-25 meV, but are enhanced for collision energies close to those of diffraction resonances. Sticking also increases with surface temperature. Desorption is a slow process which involves multiphonon processes. We show, however, how to correct the close coupling wavepacket method to account for such phenomena and obtain correct time constants for initial state decay. Desorption time constants are in the range of 20-50 ps for a surface temperature of 300 K.

  13. Effect of hydrogenation disproportionation conditions on magnetic anisotropy in Nd-Fe-B powder prepared by dynamic hydrogenation disproportionation desorption recombination

    Directory of Open Access Journals (Sweden)

    Masao Yamazaki

    2017-05-01

    Full Text Available Various anisotropic Nd-Fe-B magnetic powders were prepared by the dynamic hydrogenation disproportionation desorption recombination (d-HDDR treatment with different hydrogenation disproportionation (HD times (tHD. The resulting magnetic properties and microstructural changes were investigated. The magnetic anisotropy was decreased with increasing tHD. In the d-HDDR powders with higher magnetic anisotropy, fine (200–600 nm and coarse (600–1200 nm Nd2Fe14B grains were observed. The coarse Nd2Fe14B grains showed highly crystallographic alignment of the c-axis than fine Nd2Fe14B grains. In the highly anisotropic Nd2Fe14B d-HDDR powder, a large area fraction of lamellar-like structures consisting of NdH2 and α-Fe were observed after HD treatment. Furthermore, the mean diameter of the lamellar-like regions, where lamellar-like structures orientate to the same direction in the HD-treated alloys was close to that of coarse Nd2Fe14B grains after d-HDDR treatment. Thus, the lamellar-like regions were converted into the crystallographically aligned coarse Nd2Fe14B grains during desorption recombination treatment, and magnetic anisotropy is closely related to the volume fraction of lamellar-like regions observed after HD treatment.

  14. THE EFFECT OF MAGNETITE (Fe3O4CATALYST FROM IRON SANDS ON DESORPTION TEMPERATURE OF MgH2 HYDROGEN STORAGE MATERIAL

    Directory of Open Access Journals (Sweden)

    Maulinda Maulinda

    2016-03-01

    Full Text Available One of the future technologies for a safe hydrogen storage media is  metal hydrides. Currently, Mg-based metal hydride has a safety factor and efficient for vehicle applications. However, the thermodynamic properties of magnesium hydride (MgH2 found a relatively high temperature. High desorption temperatures caused MgH2 high thermodynamic stability resulting desorption enthalpy is also high. In this study, natural mineral (iron ore has been extracted from iron sand into powder of magnetite (Fe3O4 and used as a catalyst in an effort to improve the desorption properties of MgH2. Magnetie has been successfully extracted from iron sand using precipitation method with a purity of 85 % , where the purity of the iron sand before extracted was 81%. Then, MgH2-Fe3O4 was milling using mechanical alloying method with a variety of catalysts and milling time. The observation by XRD showed the material was reduced to nanocrystalline scale. MgH2 phase appears as the main phase. DSC test results showed with the addition of Fe3O4, the desorption temperature can be reduced up to 366oC, compared to pure pure MgH2 reached by 409o C. Furthermore, based on gravimetric test, the hydrogen release occurs at a temperature of 388o C, weight loss  of 0.66 mg during 16 minutes.

  15. Adsorption-desorption properties and characterization of crosslinked Konjac glucomannan-graft-polyacrylamide-co-sodium xanthate

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lufeng; Duan Jiacai; Miao Wenhua; Zhang Ruojie; Pan Siyi [College of Food Science and Technology, Huazhong Agricultural University, No.1, Shizishan Street, Wuhan, Hubei 430070 (China); Xu Xiaoyun, E-mail: xiaoyunxu88@gmail.com [College of Food Science and Technology, Huazhong Agricultural University, No.1, Shizishan Street, Wuhan, Hubei 430070 (China)

    2011-02-28

    A new flocculant, based on Konjac-graft-poly (acrylamide)-co-sodium xanthate (CKAX), was synthesized in aqueous solution using epichlorohydrin (ECH) as the cross-linker and ceric ammonium nitrate (CAN) as the initiator. X-ray diffraction indicated the existence of strong interaction between KGM and reactant, including intermolecular and intramolecular hydrogen bonds. Microscopy images exhibited the appropriate pore size and distribution, which might be related to a higher capacity of flocculation and adsorption. Thermo gravimetric analysis showed that the synthetic polymer could improve the thermo-stability of the natural polysaccharides, and there was a positive correlation between polymer residual weight and flocculation. The adsorption and desorption properties for copper ions indicated that the adsorption rate could be described by a pseudo-second-order rate model, and the Freundlich model provides the best fit for the resulting adsorption isotherm. The flocculant can be regenerated in HNO{sub 3} solution.

  16. Oxygen sorption and desorption properties of selected lanthanum manganites and lanthanum ferrite manganites.

    Science.gov (United States)

    Nielsen, Jimmi; Skou, Eivind M; Jacobsen, Torben

    2015-06-08

    Temperature-programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid-oxide fuel cell (SOFC) cathode materials (La(0.85) Sr(0.15)0.95 MnO(3+δ) (LSM) and La(0.60) Sr(0.40) Fe(0.80) Mn(0.20) O(3-δ) (LSFM). The powders were characterized by X-ray diffractometry, atomic force microscopy (AFM), and BET surface adsorption. Sorbed oxygen could be distinguished from oxygen originating from stoichiometry changes. The results indicated that there is one main site for oxygen sorption/desorption. The amount of sorbed oxygen was monitored over time at different temperatures. Furthermore, through data analysis it was shown that the desorption peak associated with oxygen sorption is described well by second-order desorption kinetics. This indicates that oxygen molecules dissociate upon adsorption and that the rate-determining step for the desorption reaction is a recombination of monatomic oxygen. Typical problems with re-adsorption in this kind of TPD setup were revealed to be insignificant by using simulations. Finally, different key parameters of sorption and desorption were determined, such as desorption activation energies, density of sorption sites, and adsorption and desorption reaction order. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. An investigation of the hydrogen desorption from Nd{sub 2}Fe{sub 17}H{sub x} and Dy{sub 2}Fe{sub 17}H{sub x} compounds by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas, F. [ICMPE/CNRS-UPEC, UMR 7182, 2-8, rue Henri Dunant 94320, Thiais (France); Isnard, O., E-mail: olivier.isnard@grenoble.cnrs.fr [Institut Néel du CNRS et Université Joseph Fourier, BP 166 X, 38042 Grenoble cedex 9 (France); Villeroy, B. [ICMPE/CNRS-UPEC, UMR 7182, 2-8, rue Henri Dunant 94320, Thiais (France)

    2013-06-10

    Highlights: • We investigate the hydrogen desorption from R{sub 2}Fe{sub 17}H{sub x} (R = Nd and Dy) compounds. • The heat of hydrogen desorption is 29.2 ± 0.8 kJ mol H{sup −1} for both R{sub 2}Fe{sub 17}H{sub x} family compounds. • Hydrogen desorption activation energies have been determined from DSC. • Thermodynamical data are analysed for both heavy (Dy) and light (Nd) rare earth elements in the light of the precise knowledge of the crystal structure. - Abstract: Hydrogen desorption from R{sub 2}Fe{sub 17}H{sub x} (R = Nd and Dy) compounds with x ≤ 5 has been studied using differential scanning calorimetry (DSC). Overall hydrogen binding energies are very similar in both systems regardless their different crystal structures. The heat of hydrogen desorption is 29.2 ± 0.8 kJ mol H{sup −1} for both R{sub 2}Fe{sub 17}H{sub x} family compounds. Desorption activation energies are also very close: 78 ± 8 kJ and 79 ± 4 kJ mol H{sup −1} for Nd and Dy-containing compounds, respectively. The rare earth nature modifies however the local interaction between hydrogen and the intermetallic compound. For Nd, H-atoms occupy two non-equivalent and well-defined energy sites whereas a unique energy site with a broad energy distribution is detected for Dy. This peculiar behavior is discussed in terms of the different structural properties of the light (Nd) and heavy (Dy) rare-earth R{sub 2}Fe{sub 17} compounds.

  18. Carriers reactivation in p{sup +}-type porous silicon accompanies hydrogen desorption

    Energy Technology Data Exchange (ETDEWEB)

    Rivolo, P.; Geobaldo, F.; Salvador, G.P.; Pallavidino, L.; Garrone, E. [Dip. Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Ugliengo, P. [Dip. Chimica IFM, Universita di Torino, Via Giuria 7, 10125 Torino (Italy)

    2005-06-01

    FTIR spectra of p{sup +}-type mesoporous silicon (m-PS) outgassed in the 300-600 K range show a loss of transparency with increasing temperature, more pronounced at low frequencies. This is evidence of free-carrier formation. Previous work (F. Geobaldo et al., Sensors and Actuators B, in press [1]) concerning the reversible interaction of NO{sub 2} and NH{sub 3} has shown the presence at the surface of adsorption sites involving Si/B pairs. Thermal treatment of the sample causes desorption of molecular hydrogen, released through the homolytic splitting of Si-H bonds. Besides meeting each other forming a H{sub 2} molecule, H atoms may interact with an adsorption site, by creating a new H-Si-B bond. This new bond needs one additional electron to be formed and injection of a hole takes place into the solid. At higher temperatures, surface hydrogen is almost totally removed and the sample transparency recovered. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Diffusion, adsorption, and desorption of molecular hydrogen on graphene and in graphite.

    Science.gov (United States)

    Petucci, Justin; LeBlond, Carl; Karimi, Majid; Vidali, Gianfranco

    2013-07-28

    The diffusion of molecular hydrogen (H2) on a layer of graphene and in the interlayer space between the layers of graphite is studied using molecular dynamics computer simulations. The interatomic interactions were modeled by an Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential. Molecular statics calculations of H2 on graphene indicate binding energies ranging from 41 meV to 54 meV and migration barriers ranging from 3 meV to 12 meV. The potential energy surface of an H2 molecule on graphene, with the full relaxations of molecular hydrogen and carbon atoms is calculated. Barriers for the formation of H2 through the Langmuir-Hinshelwood mechanism are calculated. Molecular dynamics calculations of mean square displacements and average surface lifetimes of H2 on graphene at various temperatures indicate a diffusion barrier of 9.8 meV and a desorption barrier of 28.7 meV. Similar calculations for the diffusion of H2 in the interlayer space between the graphite sheets indicate high and low temperature regimes for the diffusion with barriers of 51.2 meV and 11.5 meV. Our results are compared with those of first principles.

  20. Hydrogenation properties of Mg-Al alloys

    DEFF Research Database (Denmark)

    Andreasen, Anders

    2008-01-01

    . Further, it is found that the kinetics of hydrogenation, as well dehydrogenation, may be significantly improved by alloying compared to pure Mg. The expense of these improvements of the hydrogenation/dehydrogenation properties is a lower gravimetric hydrogen density in the hydrogenated product, (C) 2008...

  1. Molecular Beam-Thermal Desorption Spectrometry (MB-TDS) Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes.

    Science.gov (United States)

    Lobo, Rui F M; Santos, Diogo M F; Sequeira, Cesar A C; Ribeiro, Jorge H F

    2012-02-06

    Different types of experimental studies are performed using the hydrogen storage alloy (HSA) MlNi3.6Co0.85Al0.3Mn0.3 (Ml: La-rich mischmetal), chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC). The recently developed molecular beam-thermal desorption spectrometry (MB-TDS) technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA), and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA) using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption.

  2. Molecular Beam-Thermal Desorption Spectrometry (MB-TDS Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes

    Directory of Open Access Journals (Sweden)

    Jorge H. F. Ribeiro

    2012-02-01

    Full Text Available Different types of experimental studies are performed using the hydrogen storage alloy (HSA MlNi3.6Co0.85Al0.3Mn0.3 (Ml: La-rich mischmetal, chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC. The recently developed molecular beam—thermal desorption spectrometry (MB-TDS technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA, and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption.

  3. Molecular Beam-Thermal Desorption Spectrometry (MB-TDS) Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes

    Science.gov (United States)

    Lobo, Rui F. M.; Santos, Diogo M. F.; Sequeira, Cesar A. C.; Ribeiro, Jorge H. F.

    2012-01-01

    Different types of experimental studies are performed using the hydrogen storage alloy (HSA) MlNi3.6Co0.85Al0.3Mn0.3 (Ml: La-rich mischmetal), chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC). The recently developed molecular beam—thermal desorption spectrometry (MB-TDS) technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA), and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA) using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption. PMID:28817043

  4. Oxygen Sorption and Desorption Properties of Selected Lanthanum Manganites and Lanthanum Ferrite Manganites

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Skou, Eivind M.; Jacobsen, Torben

    2015-01-01

    Temperature‐programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid‐oxide fuel cell (SOFC) cathode materials (La0.85Sr0.15)0.95MnO3+δ (LSM) and La0.60Sr0.40Fe0.80Mn0.20O3‐δ (LSFM). The powders were characteriz...

  5. Properties of MgAl alloys in relation to hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Andreasen, Anders

    2005-08-01

    Magnesium theoretically stores 7.6 wt. % hydrogen, although it requires heating to above 300 degrees C in order to release hydrogen. This limits its use for mobile application. However, due to its low price and abundance magnesium should still be considered as a potential candidate for hydrogen storage e.g. in stationary applications. In this report the properties of Mg-Al alloys are reviewed in relation to solid state hydrogen storage Alloying with Al reduces the hydrogen capacity since Al does not form a hydride under conventional hydriding conditions, however both the thermodynamical properties (lower desorption temperature), and kinetics of hydrogenation/dehydrogenation are improved. In addition to this, the low price of the hydride is retained along with improved heat transfer properties and improved resistance towards oxygen contamination. (au)

  6. Spatially resolved protein hydrogen exchange measured by matrix-assisted laser desorption ionization in-source decay

    DEFF Research Database (Denmark)

    Rand, Kasper D; Bache, Nicolai; Nedertoft, Morten M

    2011-01-01

    Mass spectrometry has become a powerful tool for measuring protein hydrogen exchange and thereby reveal the structural dynamics of proteins in solution. Here we describe the successful application of a matrix-assisted laser desorption ionization (MALDI) mass spectrometry approach based on in......-source decay (ISD) to measure spatially resolved amide backbone hydrogen exchange. By irradiating deuterated protein molecules in a crystalline matrix with a high laser fluence, they undergo prompt fragmentation. Spatially resolved deuteration levels are readily obtained by mass analysis of consecutive...... fragment ions. MALDI ISD analysis of deuterated cytochrome c yielded an extensive series of c-fragment ions which originate from cleavage of nearly all N-C(α) bonds (Cys17 to Glu104) allowing for a detailed analysis of the deuterium content of the backbone amides. While hydrogen scrambling can be major...

  7. Modulated hydrogen beam study of adsorption-induced desorption of deuterium from Si(100)-3×1:D surfaces

    Science.gov (United States)

    Rahman, F.; Kuroda, M.; Kiyonaga, T.; Khanom, F.; Tsurumaki, H.; Inanaga, S.; Namiki, A.

    2004-08-01

    We have studied the kinetic mechanism of the adsorption-induced-desorption (AID) reaction, H+D/Si(100)→D2. Using a modulated atomic hydrogen beam, two different types of AID reaction are revealed: one is the fast AID reaction occurring only at the beam on-cycles and the other the slow AID reaction occurring even at the beam off-cycles. Both the fast and slow AID reactions show the different dependence on surface temperature Ts, suggesting that their kinetic mechanisms are different. The fast AID reaction overwhelms the slow one in the desorption yield for 300 K⩽Ts⩽650 K. It proceeds along a first-order kinetics with respect to the incident H flux. Based on the experimental results, both two AID reactions are suggested to occur only on the 3×1 dihydride phase accumulated during surface exposure to H atoms. Possible mechanisms for the AID reactions are discussed.

  8. The development of microstructure during hydrogenation-disproportionation-desorption-recombination treatment of sintered neodymium-iron-boron-type magnets

    Science.gov (United States)

    Sheridan, R. S.; Harris, I. R.; Walton, A.

    2016-03-01

    The hydrogen absorption and desorption characteristics of the hydrogenation disproportionation desorption and recombination (HDDR) process on scrap sintered neodymium-iron-boron (NdFeB) type magnets have been investigated. At each stage of the process, the microstructural changes have been studied using high resolution scanning electron microscopy. It was found that the disproportionation reaction initiates at grain boundaries and triple points and then propagates towards the centre of the matrix grains. This process was accelerated at particle surfaces and at free surfaces produced by any cracks in the powder particles. However, the recombination reaction appeared to initiate randomly throughout the particles with no apparent preference for particle surfaces or internal cracks. During the hydrogenation of the grain boundaries and triple junctions, the disproportionation reaction was, however, affected by the much higher oxygen content of the sintered NdFeB compared with that of the as-cast NdFeB alloys. Throughout the entire HDDR reaction the oxidised triple junctions (from the sintered structure) remained unreacted and hence, remained in their original form in the fine recombined microstructure. This resulted in a very significant reduction in the proportion of cavitation in the final microstructure and this could lend to improved consolidation in the recycled magnets.

  9. Thermodynamic properties of hydrogen-helium plasmas.

    Science.gov (United States)

    Nelson, H. F.

    1972-01-01

    Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.

  10. Moisture sorption–desorption characteristics and the corresponding thermodynamic properties of carvedilol phosphate

    Directory of Open Access Journals (Sweden)

    Ravikiran Allada

    2017-01-01

    Full Text Available Aims: Carvedilol phosphate (CDP is a nonselective beta-blocker used for the treatment of heart failures and hypertension. In this work, moisture sorption–desorption characteristics and thermodynamic properties of CDP have been investigated. Materials and Methods: The isotherms were determined using dynamic vapor sorption analyzer at different humidity conditions (0%–90% relative humidity and three pharmaceutically relevant temperatures (20°C, 30°C, and 40°C. The experimental sorption data determined were fitted to various models, namely, Brunauer–Emmett–Teller; Guggenheim-Anderson-De Boer (GAB; Peleg; and modified GAB. Isosteric heats of sorption were evaluated through the direct use of sorption isotherms by means of the Clausius-Clapeyron equation. Statistical Analysis Used: The sorption model parameters were determined from the experimental sorption data using nonlinear regression analysis, and mean relative percentage deviation (P, correlation (Correl, root mean square error, and model efficiency were considered as the criteria to select the best fit model. Results: The sorption–desorption isotherms have sigmoidal shape – confirming to Type II isotherms. Based on the statistical data analysis, modified GAB model was found to be more adequate to explain sorption characteristics of CDP. It is noted that the rate of adsorption and desorption is specific to the temperature at which it was being studied. It is observed that isosteric heat of sorption decreased with increasing equilibrium moisture content. Conclusions: The calculation of the thermodynamic properties was further used to draw an understanding of the properties of water and energy requirements associated with the sorption behavior. The sorption–desorption data and the set of equations are useful in the simulation of processing, handling, and storage of CDP and further behavior during manufacture and storage of CDP formulations.

  11. Moisture Sorption–desorption Characteristics and the Corresponding Thermodynamic Properties of Carvedilol Phosphate

    Science.gov (United States)

    Allada, Ravikiran; Maruthapillai, Arthanareeswari; Palanisamy, Kamaraj; Chappa, Praveen

    2017-01-01

    Aims: Carvedilol phosphate (CDP) is a nonselective beta-blocker used for the treatment of heart failures and hypertension. In this work, moisture sorption–desorption characteristics and thermodynamic properties of CDP have been investigated. Materials and Methods: The isotherms were determined using dynamic vapor sorption analyzer at different humidity conditions (0%–90% relative humidity) and three pharmaceutically relevant temperatures (20°C, 30°C, and 40°C). The experimental sorption data determined were fitted to various models, namely, Brunauer–Emmett–Teller; Guggenheim-Anderson-De Boer (GAB); Peleg; and modified GAB. Isosteric heats of sorption were evaluated through the direct use of sorption isotherms by means of the Clausius-Clapeyron equation. Statistical Analysis Used: The sorption model parameters were determined from the experimental sorption data using nonlinear regression analysis, and mean relative percentage deviation (P), correlation (Correl), root mean square error, and model efficiency were considered as the criteria to select the best fit model. Results: The sorption–desorption isotherms have sigmoidal shape – confirming to Type II isotherms. Based on the statistical data analysis, modified GAB model was found to be more adequate to explain sorption characteristics of CDP. It is noted that the rate of adsorption and desorption is specific to the temperature at which it was being studied. It is observed that isosteric heat of sorption decreased with increasing equilibrium moisture content. Conclusions: The calculation of the thermodynamic properties was further used to draw an understanding of the properties of water and energy requirements associated with the sorption behavior. The sorption–desorption data and the set of equations are useful in the simulation of processing, handling, and storage of CDP and further behavior during manufacture and storage of CDP formulations. PMID:28584488

  12. Moisture Sorption-desorption Characteristics and the Corresponding Thermodynamic Properties of Carvedilol Phosphate.

    Science.gov (United States)

    Allada, Ravikiran; Maruthapillai, Arthanareeswari; Palanisamy, Kamaraj; Chappa, Praveen

    2017-01-01

    Carvedilol phosphate (CDP) is a nonselective beta-blocker used for the treatment of heart failures and hypertension. In this work, moisture sorption-desorption characteristics and thermodynamic properties of CDP have been investigated. The isotherms were determined using dynamic vapor sorption analyzer at different humidity conditions (0%-90% relative humidity) and three pharmaceutically relevant temperatures (20°C, 30°C, and 40°C). The experimental sorption data determined were fitted to various models, namely, Brunauer-Emmett-Teller; Guggenheim-Anderson-De Boer (GAB); Peleg; and modified GAB. Isosteric heats of sorption were evaluated through the direct use of sorption isotherms by means of the Clausius-Clapeyron equation. The sorption model parameters were determined from the experimental sorption data using nonlinear regression analysis, and mean relative percentage deviation (P), correlation (Correl), root mean square error, and model efficiency were considered as the criteria to select the best fit model. The sorption-desorption isotherms have sigmoidal shape - confirming to Type II isotherms. Based on the statistical data analysis, modified GAB model was found to be more adequate to explain sorption characteristics of CDP. It is noted that the rate of adsorption and desorption is specific to the temperature at which it was being studied. It is observed that isosteric heat of sorption decreased with increasing equilibrium moisture content. The calculation of the thermodynamic properties was further used to draw an understanding of the properties of water and energy requirements associated with the sorption behavior. The sorption-desorption data and the set of equations are useful in the simulation of processing, handling, and storage of CDP and further behavior during manufacture and storage of CDP formulations.

  13. Ultra high vacuum high precision low background setup with temperature control for thermal desorption mass spectroscopy (TDA-MS) of hydrogen in metals.

    Science.gov (United States)

    Merzlikin, Sergiy V; Borodin, S; Vogel, D; Rohwerder, M

    2015-05-01

    In this work, a newly developed UHV-based high precision low background setup for hydrogen thermal desorption analysis (TDA) of metallic samples is presented. Using an infrared heating with a low thermal capacity enables a precise control of the temperature and rapid cool down of the measurement chamber. This novel TDA-set up is superior in sensitivity to almost every standard hydrogen analyzer available commercially due to the special design of the measurement chamber, resulting in a very low hydrogen background. No effects of background drift characteristic as for carrier gas based TDA instruments were observed, ensuring linearity and reproducibility of the analysis. This setup will prove to be valuable for detailed investigations of hydrogen trapping sites in steels and other alloys. With a determined limit of detection of 5.9×10(-3)µg g(-1) hydrogen the developed instrument is able to determine extremely low hydrogen amounts even at very low hydrogen desorption rates. This work clearly demonstrates the great potential of ultra-high vacuum thermal desorption mass spectroscopy instrumentation. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Actuation of Pneumatic Artificial Muscle via Hydrogen Absorption/Desorption of Metal Hydride-LaNi5

    Directory of Open Access Journals (Sweden)

    Thanana Nuchkrua

    2015-01-01

    Full Text Available This paper presents experimental studies on mechanical actuations of a pneumatic artificial muscle (PAM, which is driven by hydrogen gas based metal hydride (MH. The dynamic performances of hydrogen absorption/desorption, taking place within a MH reactor, are controlled via implementing cooling/heating effects of a thermoelectric module (TEM. Hydrogen pressure is applied as a driving force to commanding work outputs of the PAM as desired mechanical actuations. Due to strong inherent nonlinearity, a conventional proportional integral derivative (PID control law is not capable of regulating thermodynamic variables of the HM reaction according to desired performances of the PAM. In this study, the fuzzy adaptive PID control is proposed in manipulating the MH reaction via the TEM. This viability of the proposed methodology is confirmed by the fact that the gains of PID control law are adapted by fuzzy rule-based tuning scheme at various operating conditions of the MH reactor. The experimental results show that the proposed control technique is much more effective than a PID control in both transient and steady state performances of the MH reactor for servo mechanical actuation of the PAM.

  15. Comparative analysis of the electroactive area of Pt/C PEMFC electrodes in liquid and solid polymer contact by underpotential hydrogen adsorption/desorption

    Energy Technology Data Exchange (ETDEWEB)

    Chaparro, A.M.; Martin, A.J.; Folgado, M.A.; Gallardo, B. [Dep. de Energia, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Daza, L. [Dep. de Energia, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-06-15

    Because of the different experimental conditions found in literature for the measurement of the electroactive area of Pt/C electrodes of proton exchange membrane fuel cells (PEMFC) by means of underpotential hydrogen adsorption (H{sub UPD}) voltammetry, specially concerning sweep rate and temperature, it was found necessary to perform an analysis of these parameters. With this aim, the electroactive area of PEMFC electrodes has been measured by means of H{sub UPD} voltammetry at different sweep rates and temperatures, in liquid electrolyte and solid polymer contact. Both configurations show that H{sub UPD} adsorption and desorption charges are strongly dependent on sweep rate voltage and temperature. The most common behaviour observed is a maximum in H{sub UPD} desorption charge, typically in the 100-10 mV s{sup -1} sweep rate range, whereas H{sub UPD} adsorption charge shows continuous increase with decreasing sweep rate. The decrease of desorption charge at low sweep rates is attributed to adsorbing species related with carbon support reactivity. These processes are also responsible for the increase in desorption H{sub UPD} charge at low sweep rate. At high sweep rate, both adsorption and desorption H{sub UPD} charges decrease due to limiting diffusion of protons through the microporous electrode. As a consequence, it is found that the closest approximation to the real electroactive area (i.e. the area accessible to protons) corresponds to the maximum in the H{sub UPD} desorption charge in the range of 10-100 mV s{sup -1} sweep rate. The influence of measuring temperature is also tested in the range 25 C-80 C. A dependence of the adsorption and desorption hydrogen charges is found, due to thermodynamic and kinetics factors. We observe that the processes competing with hydrogen adsorption, i.e. generation and adsorption of carbon species are enhanced with temperature, so a low measuring temperature is found as most appropriate. (author)

  16. Structural and hydrogenation properties of RE-M-Mg compounds

    Energy Technology Data Exchange (ETDEWEB)

    Dorogova, M.; Paul-Boncour, V. [Laboratoire de Chimie Metallurgique des Terres Rares (LCMTR), CNRS, 94 - Thiais (France); Pavlyuk, V.; Solokha, P. [Ivano-Franko National Univ. of Lviv, Dept. of Inorganic Chemistry, Lviv (Ukraine)

    2007-07-01

    Complete text of publication follows: The purpose of the current work was to synthesize and investigate the hydrogen storage properties of ternary alloys from RE-M-Mg systems (RE-rare earth metals, M - transition element such as Ni and Cu). Alloys based on magnesium are known to store high amount of hydrogen (up to 7.7 wt.%) reversibly. Mg{sub 2}Ni-based alloys offer also very high capacity (up to 4 wt.% H{sub 2}). This storage capacity coupled with a low price and reversibility suggests that magnesium and magnesium-based alloys could be advantageous for use in battery electrodes and gaseous - hydrogen storage systems. Therefore, Mg-based and Mg{sub 2}Ni-based materials were in the focus of our studies. The REMg{sub 2}Cu{sub 9} ternary compounds (where RE - Y, La-Nd, Sm-Ho, Yb) [1] and REMg{sub 2}(CuNi){sub 9} alloys (where RE = La, Tb, Pr) were synthesised. Crystal structure determination and microstructural characterisation were performed. LaMg{sub 2}Cu{sub 9}, TbMg{sub 2}Cu{sub 9}, PrMg{sub 2}Cu{sub 9}, LaNi{sub 5}Cu{sub 4}Mg{sub 2} and TbNi{sub 3}Cu{sub 6}Mg{sub 2} were chosen for the investigation of hydrogen storage properties. TbMg{sub 2}Cu{sub 9} and PrMg{sub 2}Cu{sub 9} did not absorb hydrogen in pressure range 1 to 10 bar and at the ambient temperature. LaMg{sub 2}Cu{sub 9} absorbs 3 H/f.u (1.004 wt%) under 100 bar and at 25 C. LaMg{sub 2}Cu{sub 4}Ni{sub 5} absorbs 1.6 H/f.u (1.002 wt%) under 10 bar and at 25 C. Pressure - hydrogen concentration isotherm was measured. TbMg{sub 2}Ni{sub 3}Cu{sub 6} absorbs 3 H/f.u (1.004 wt%) under 100 bar and at 25 C. All the samples needed to be activated by heat treatment under vacuum followed by several absorption - desorption cycles.

  17. Theoretical study of hydrogen absorption-desorption on LaNi3.8Al1.2-xMnx using statistical physics treatment

    Science.gov (United States)

    Bouaziz, Nadia; Ben Manaa, Marwa; Ben Lamine, Abdelmottaleb

    2017-11-01

    The hydrogen absorption-desorption isotherms on LaNi3.8Al1.2-xMnx alloy at temperature T = 433 K is studied through various theoretical models. The analytical expressions of these models were deduced exploiting the grand canonical ensemble in statistical physics by taking some simplifying hypotheses. Among these models an adequate model which presents a good correlation with the experimental curves has been selected. The physicochemical parameters intervening in the absorption-desorption processes and involved in the model expressions could be directly deduced from the experimental isotherms by numerical simulation. Six parameters of the model are adjusted, namely the numbers of hydrogen atoms per site n1 and n2, the receptor site densities N1m and N2m, and the energetic parameters P1 and P2. The behaviors of these parameters are discussed in relation with absorption and desorption processes to better understand and compare these phenomena. Thanks to the energetic parameters, we calculated the sorption energies which are typically ranged between 266 and 269.4 KJ/mol for absorption process and between 267 and 269.5 KJ/mol for desorption process comparable to usual chemical bond energies. Using the adopted model expression, the thermodynamic potential functions which govern the absorption/desorption process such as internal energy Eint, free enthalpy of Gibbs G and entropy Sa are derived.

  18. Principles of hydrogen radical mediated peptide/protein fragmentation during matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Asakawa, Daiki

    2016-07-01

    Matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) is a very easy way to obtain large sequence tags and, thereby, reliable identification of peptides and proteins. Recently discovered new matrices have enhanced the MALDI-ISD yield and opened new research avenues. The use of reducing and oxidizing matrices for MALDI-ISD of peptides and proteins favors the production of fragmentation pathways involving "hydrogen-abundant" and "hydrogen-deficient" radical precursors, respectively. Since an oxidizing matrix provides information on peptide/protein sequences complementary to that obtained with a reducing matrix, MALDI-ISD employing both reducing and oxidizing matrices is a potentially useful strategy for de novo peptide sequencing. Moreover, a pseudo-MS(3) method provides sequence information about N- and C-terminus extremities in proteins and allows N- and C-terminal side fragments to be discriminated within the complex MALDI-ISD mass spectrum. The combination of high mass resolution of a Fourier transform-ion cyclotron resonance (FTICR) analyzer and the software suitable for MALDI-ISD facilitates the interpretation of MALDI-ISD mass spectra. A deeper understanding of the MALDI-ISD process is necessary to fully exploit this method. Thus, this review focuses first on the mechanisms underlying MALDI-ISD processes, followed by a discussion of MALDI-ISD applications in the field of proteomics. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:535-556, 2016. © 2014 Wiley Periodicals, Inc.

  19. Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    DEFF Research Database (Denmark)

    Bialy, Agata; Jensen, Peter Bjerre; Blanchard, Didier

    2015-01-01

    Metal halide ammines are very attractive materials for ammonia absorption and storage—applications where the practically accessible or usable gravimetric and volumetric storage densities are of critical importance. Here we present, that by combining advanced computational materials prediction...... with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides...

  20. Investigations in single and multi-component adsorption and desorption of low alkanes in a hydrogen mixture at a carbon adsorbent in view of the rating of alternating pressure systems for hydrogen production. Untersuchungen zur Ein- und Mehrkomponenten- Ad- und Desorption von niedrigen Alkanen im Gemisch mit Wasserstoff an einem Kohlenstoffadsorbens im Hinblick auf die Auslegung von DWA-Anlagen zur Wasserstoffgewinnung

    Energy Technology Data Exchange (ETDEWEB)

    Eichholtz, A.

    1984-07-06

    The investigations relate to the alternating-pressure adsorption and desorption of the pure gases hydrogen, methane, ethane, and propane, as well as of the binary gas mixtures hydrogen-methane, hydrogen-ethane, methane-ethane and ethane-propane at a carbonated molecular sieve. The cycle duration of such an alternating-pressure process and consequently the size of the separating reactors are determined by the component having the lowest adsorption effect during the adsorption phase, respectively by the one requiring the longest desorption time during the desorption phase. Assuming that the entire process of adsorption will be a very fast one, the break-through times of the components to be separated from a gas mixture at the adsorber exit, and thus the maximum possible cycle duration of the entire process, can be previously calculated by means of an equilibrium-zone model. (PW).

  1. Retention property of deuterium for fuel recovery in divertor by using hydrogen storage material

    Science.gov (United States)

    Mera, Saori; Tonegawa, Akira; Matsumura, Yoshihito; Sato, Kohnosuke; Kawamura, Kazutaka

    2014-10-01

    Magnetic confinement fusion reactor by using Deuterium and Tritium of hydrogen isotope as fuels is suggested as one of the future energy source. Most fuels don't react and are exhausted out of fusion reactor. Especially, Tritium is radioisotope and rarely exists in nature, so fuels recovery is necessary. This poster presentation will explain about research new fuel recovery method by using hydrogen storage materials in divertor simulator TPD-Sheet IV. Samples are tungsten coated with titanium; tungsten of various thickness, and titanium films deposited by ion plating on tungsten substrates. The sample surface temperature is measured by radiation thermometer. Retention property of deuterium after deuterium plasma irradiation was examined with thermal desorption spectroscopy (TDS). As a result, the TDS measurement shows that deuterium is retained in titanium. Therefore, Titanium as a hydrogen storage material expects to be possible to use separating and recovering fuel particles in divertor.

  2. Improvement in the hydrogen desorption from MgH2 upon transition metals doping: A hybrid density functional calculations

    Directory of Open Access Journals (Sweden)

    Tanveer Hussain

    2013-10-01

    Full Text Available This study deals with the investigations of structural, electronic and thermodynamic properties of MgH2 doped with selected transition metals (TMs by means of hybrid density functional theory (PBE0. On the structural side, the calculated lattice parameters and equilibrium volumes increase in case of Sc, Zr and Y opposite to all the other dopants indicating volumetrically increased hydrogen density. Except Fe, all the dopants improve the kinetics of MgH2 by reducing the heat of adsorption with Cu, Nb, Ni and V proving more efficient than others studied TM’s. The electronic properties have been studied by density of states and correlated with hydrogen adsorption energies.

  3. Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

    Science.gov (United States)

    Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

    2017-10-01

    In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

  4. Ground state structures and properties of small hydrogenated silicon ...

    Indian Academy of Sciences (India)

    We present results for ground state structures and properties of small hydrogenated silicon clusters using the Car–Parrinello molecular dynamics with simulated annealing. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen can form a bridge like Si–H–Si bond connecting two silicon ...

  5. Ground state structures and properties of small hydrogenated silicon ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. We present results for ground state structures and properties of small hydrogenated silicon clus- ters using the Car–Parrinello molecular dynamics with simulated annealing. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen can form a bridge like Si–H–Si bond connecting two ...

  6. Effect of the calcium halides, CaCl{sub 2} and CaBr{sub 2}, on hydrogen desorption in the Li–Mg–N–H system

    Energy Technology Data Exchange (ETDEWEB)

    Bill, Rachel F. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Reed, Daniel; Book, David [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Anderson, Paul A., E-mail: p.a.anderson@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • H{sub 2} desorption from 2LiNH{sub 2}–MgH{sub 2}–xCaX{sub 2} (x = 0, 0.1, 0.15; X = Cl, Br) samples studied. • Addition of calcium halides reduced the desorption temperature in all samples. • Peak H{sub 2} release was around 150 °C lower in ball-milled than in hand-ground samples. • The 2LiNH{sub 2}–MgH{sub 2}–0.15CaBr{sub 2} sample showed the lowest peak desorption temperature. • CaBr{sub 2} reduced the activation energy to 78.8 kJ mol{sup −1}, 24% less than the undoped sample. - Abstract: Calcium-halide-doped lithium amide–magnesium hydride samples were prepared both by hand-grinding and ball-milling 2LiNH{sub 2}–MgH{sub 2}–xCaX{sub 2} (x = 0, 0.1, and 0.15; X = Cl or Br). The addition of calcium halides reduced the hydrogen desorption temperature in all samples. The ball-milled undoped sample (2LiNH{sub 2}–MgH{sub 2}) began to desorb hydrogen at around 125 °C and peaked at 170 °C. Hydrogen desorption from the 0.15 mol CaCl{sub 2}-containing sample began ca 30 °C lower than that of the undoped sample and peaked at 150 °C. Both the onset and peak temperatures of the CaBr{sub 2} sample (x = 0.15) were reduced by 15 °C compared to the chloride. Kissinger’s method was used to calculate the effective activation energy (E{sub a}) for the systems: E{sub a} for the 0.15 mol CaCl{sub 2}-containing sample was found to be 91.8 kJ mol{sup −1} and the value for the 0.15 mol CaBr{sub 2}-containing sample was 78.8 kJ mol{sup −1}.

  7. Composition-Dependent Reaction Pathways and Hydrogen Storage Properties of LiBH₄/Mg(AlH₄)₂ Composites.

    Science.gov (United States)

    Pang, Yuepeng; Liu, Yongfeng; Zhang, Xin; Li, Qian; Gao, Mingxia; Pan, Hongge

    2015-11-01

    Herein, an initial attempt to understand the relationships between hydrogen storage properties, reaction pathways, and material compositions in LiBH4-x Mg(AlH4)2 composites is demonstrated. The hydrogen storage properties and the reaction pathways for hydrogen release from LiBH4-x Mg(AlH4)2 composites with x=1/6, 1/4, and 1/2 were systematically investigated. All of the composites exhibit a four-step dehydrogenation event upon heating, but the pathways for hydrogen desorption/absorption are varied with decreasing LiBH4/Mg(AlH4)2 molar ratios. Thermodynamic and kinetic investigations reveal that different x values lead to different enthalpy changes for the third and fourth dehydrogenation steps and varied apparent activation energies for the first, second, and third dehydrogenation steps. Thermodynamic and kinetic destabilization caused by the presence of Mg(AlH4)2 is likely to be responsible for the different hydrogen desorption/absorption performances of the LiBH4-x Mg(AlH4)2 composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Properties of matrix-assisted laser desorption. Measurements with a time-to-digital converter.

    Science.gov (United States)

    Ens, W; Mao, Y; Mayer, F; Standing, K G

    1991-03-01

    Some properties of matrix-assisted laser desorption have been studied using single-ion-counting methods and a time-to-digital converter. The methods allow examination of the process for irradiances near the reported threshold for observation with a transient recorder. All measurements were made using bovine insulin as a test compound. We present direct evidence that an irradiance threshold near 10(6) W cm-2 exists for ion production, and that the process is a collective effect, either involving a large number of molecular ions (approximately 10(4) in a successful event or none at all. Above the threshold, the yield is found to scale with a high power (4th to 6th) of the irradiance. Measurements of initial velocity distributions indicate an axial velocity spread corresponding to approximately 50 eV and a radial velocity spread corresponding to approximately 2.4 eV. Thus the ejection or extraction mechanism appears to be strongly asymmetric.

  9. Properties of carbonaceous-palladium hydrogen sensor

    Science.gov (United States)

    Kamińska, Anna; Krawczyk, Sławomir; Wronka, Halina; Czerwosz, ElŻbieta; Firek, Piotr; Kalenik, Jerzy; Szmidt, Jan

    2013-07-01

    In this paper we present studies of hydrogen sensors based on nanostructural C-Pd films deposited on alundum substrate with silver or titanium electrodes. These C-Pd films were prepared by PVD method. Films were characterized by SEM and EDS. Sensitivity of films toward hydrogen were measured in specially prepare experimental set-up with small chamber (50ml). Response time was also registered for different percentage of hydrogen / nitrogen mixture (up to 1% of hydrogen).

  10. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  11. Effects of hydrogen adsorption on the properties of double wall BN and (BN){sub x}C{sub y} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, A. [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58059-900 João Pessoa, PB (Brazil); Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58059-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia – Campus Vitoria da Conquista, Avenida Amazonas 3150, 45030-220 Vitória da Conquista, BA (Brazil)

    2016-01-15

    In the present contribution, we apply first-principles calculations, based on the density functional theory, to study the effects of hydrogen adsorption on the structural and electronic properties of boron nitride and hybrid carbon–boron nitride double wall nanotubes. The results demonstrate that the hydrogen decoration induces significant structural deformation and an appreciable reduction in the gap energy. When the number of hydrogen atoms introduced on the outer wall is increased, desorption of hydrogen pairs are observed. The calculations indicate that each adsorbed hydrogen atom induces a structural deformation with an energetic cost of about 68 meV/atom. It is also found that the introduction of hydrogen atoms can be applied as an efficient tool for tuning the electronic properties of such structures. - Graphical abstract: Localized density of states of a hydrogenated double wall boron nitride nanotube. Some hydrogen pairs are desorbed, forming H{sub 2} molecules. - Highlights: • Hydrogenation induces structural deformation and reduction in the gap energy. • Each H atom induces a deformation with an energetic cost of about 68 meV/atom. • In some cases, desorption of H pairs from the outer wall is observed.

  12. Hydrogen release properties of lithium alanate for application to fuel cell propulsion systems

    Science.gov (United States)

    Corbo, P.; Migliardini, F.; Veneri, O.

    In this paper the results of an experimental study on LiAlH 4 (lithium alanate) as hydrogen source for fuel cell propulsion systems are reported. The compound examined in this work was selected as reference material for light metal hydrides, because of its high hydrogen content (10.5 wt.%) and interesting desorption kinetic properties at moderate temperatures. Thermal dynamic and kinetic of hydrogen release from this hydride were investigated using a fixed bed reactor to evaluate the effect of heating procedure, carrier gas flow rate and sample form. The aim of this study was to characterize the lithium alanate decomposition through the reaction steps leading to the formation of Li 3AlH 6 and LiH. A hydrogen tank was designed and realized to contain pellets of lithium alanate as feeding for a fuel cell propulsion system based on a 2-kW Polymeric Electrolyte Fuel Cell (PEFC) stack. The fuel cell system was integrated into the power train comprising DC-DC converter, energy storage systems and electric drive for moped applications (3 kW). The experiments on the power train were conducted on a test bench able to simulate the vehicle behaviour and road characteristics on specific driving cycles. In particular the efficiencies of individual components and overall power train were analyzed evidencing the energy requirements of the hydrogen storage material.

  13. Preparation of Si-carbon nanotube composite by decomposition of tetramethylsilane (TMS and its hydrogen storage property

    Directory of Open Access Journals (Sweden)

    Tatsumi Ishihara, Masashi Nakasu, Isamu Yasuda and Hiroshige Matsumoto

    2006-01-01

    Full Text Available Hydrogen storage property of Si-carbon nanotube composite was studied. It was found that the carbon nanotube coated Si particle was prepared by the decomposition of tetramethylsilane by using Ni catalyst. The obtained composite was consisted of the spherical Si particle with 300 nm diameter and the surface of Si particle was coated with carbon nanotube with 10 nm diameter. The obtained Si-carbon nanotube composite shows a fairly large hydrogen storage capacity of 2.5 wt%. The amount of storage H2 increased with increasing the preparation temperature and the largest hydrogen storage amount could be achieved at 1273 K for 6 h. Fairly large hydrogen storage capacity could be sustained after 3 cycles of adsorption and desorption.

  14. Characterization of hydrogen species on metal-oxide surfaces by electron-stimulated desorption: TiO/sub 2/ and SrTiO/sub 3/*

    Energy Technology Data Exchange (ETDEWEB)

    Knotek, M.L.

    1979-01-01

    The hydrogen species on TiO/sub 2/ and SrTiO/sub 3/ have been characterized using the site specificity of electron-excited Auger Stimulated Desorption (ASD). Hydrogen is found to be bonded to surface Ti's in hydride-type bonds, to subsurface or bridgebonded O's in a hydroxyl-like bond, or be part of a surface hydroxyl. On SrTiO/sub 3/ the Ti-H and surface OH species are also found plus a high density of Sr-H and very little Sr-OH bonding. The general features of ASD, both electron- and photon-excited, are discussed.

  15. The effects of the biogeochemical properties of clay minerals on the Pb sorption and desorption in various redox condition

    Science.gov (United States)

    Koo, T. H.; Kim, J. Y.; Kim, J. W.

    2016-12-01

    The fate and transportation of hazardous trace metal in soil environment can be controlled by various factors including temperature, geological location, properties of bed rock or sediment, human behavior, and biogeochemical reactions. The sorption and desorption process is one of the major process for control the transportation of trace metal in soil-water system. Nonetheless, few studies were focused on the biological controlling parameters, particularly redox reaction of structural metal of clay minerals. Thus, the objective of the present study is to investigate the correlation between the sorption and desorption reaction of Pb and biogeochemical properties of clay minerals. The effects of redox state of structural Fe and layer charge of the minerals on the migration/speciation of Pb at the various geochemical environment will be elucidated. The Fe-rich smectite, nontronite (NAu-1), and bulk soil samples which were collected from abandoned mine areas were reduced by microbial respiration by Shewanella Oneidensis MR-1 and/or Na-dithionite to various oxidation state of structural Fe. Then the Pb-stock solution made with common lead and nitric acid were spiked into the mineral/soil slurry with various Pb concentration to test the sorption and desorption reaction upto 7 days. The reaction was stopped at each time point by freezing the pellet and supernatant separately after centrifugation. Then the concentration and stable isotope ratio of Pb in the supernatant were measured using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Multicollector (MC)-ICP-MS. The structural as well as chemical modification on nontronite and bulk soil sample were measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) and wet chemistry analysis. The changes in Pb species in supernatant by sorption and desorption and its consequences on the clay structural/biogeochemical properties will be discussed.

  16. Effect of multi-wall carbon nanotubes supported nano-nickel and TiF{sub 3} addition on hydrogen storage properties of magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wei; Zhu, Yunfeng, E-mail: yfzhu@njtech.edu.cn; Zhang, Jiguang; Liu, Yana; Yang, Yang; Mao, Qifeng; Li, Liquan

    2016-06-05

    Multi-wall carbon nanotubes supported nano-nickel (Ni/MWCNTs) with superior catalytic effects was introduced to magnesium hydride by the process of hydriding combustion synthesis (HCS) and mechanical milling (MM). The effect of different Ni/MWCNTs contents (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) on the hydrogenation and dehydrogenation properties of the composite was investigated systematically. It is revealed that Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best comprehensive hydrogen storage properties, which absorbs 5.68 wt.% hydrogen within 100 s at 373 K and releases 4.31 wt.% hydrogen within 1800 s at 523 K under initial hydrogen pressures of 3.0 and 0.005 MPa, respectively. The in situ formed nano-Mg{sub 2}Ni and MWCNTs have excellent catalytic effect on the hydrogenation and dehydrogenation performances of MgH{sub 2}. To further improve the hydrogen absorption/desorption properties, TiF{sub 3} was added to the Mg–Ni/MWCNTs system. The result shows that TiF{sub 3} addition has little influence on the thermodynamic performance, but affects greatly the kinetic properties. The Mg{sub 85}-(Ni/MWCNTs){sub 15}-TiF{sub 3} composite exhibits an appreciably enhanced hydrogen desorption performance at low temperature, and the hydrogen desorption capacity within 1800 s at 473 K for the TiF{sub 3}-added composite is approximately four times the capacity of Mg{sub 85}-(Ni/MWCNTs){sub 15} under the same condition. The catalytic effects during hydrogenation and dehydrogenation have been discussed in the study. - Highlights: • The nanosized Ni/MWCNTs catalyst was successfully prepared. • Ni/MWCNTs shows superior catalytic effect on H absorption/desorption of Mg. • Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best hydrogen storage properties. • Ni/MWCNTs coupling with TiF{sub 3} improves the hydriding/dehydriding properties largely.

  17. Influence of soil properties and test conditions on sorption and desorption of testosterone

    Science.gov (United States)

    In this study, batch sorption and desorption experiments were conducted for testosterone using four agricultural soils and five clay minerals. Significant differences in sorption behavior were observed between abiotic and biotic systems. The Freundlich sorption coefficient Kf (µg per g)/(µg per mL) ...

  18. Effect of Magnesium Fluoride on Hydrogenation Properties of Magnesium Hydride

    Directory of Open Access Journals (Sweden)

    Pragya Jain

    2015-11-01

    Full Text Available A cost effective catalyst is of great importance for consideration of MgH2 as potential hydrogen storage material. In this regard, we investigated the catalytic role of alkaline metal fluoride on the hydrogen storage behavior of MgH2. Samples were synthesized by admixing 5 mol % MgF2 into MgH2 powder using planetary ball mill. Hydrogenation measurements made at 335 °C showed that in comparison to only 70% absorption by pure MgH2, catalyzed material absorbed 92% of theoretical capacity in less than 20 min and desorbed completely in almost the same time. Sorption studies done at lower temperatures revealed that complete absorption at temperature as low as 145 °C is possible. This is due to uniform distribution of MgF2 nano particles within the MgH2 powder. X-ray diffraction patterns also showed the presence of stable MgF2 phase that does not decompose upon hydrogen absorption-desorption. Cyclic measurements done at 310 °C showed negligible loss in the overall storage capacity with cycling. These results reveal that the presence of the chemically inert and stable MgF2 phase is responsible for good reversible characteristic and improved kinetics.

  19. Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

    Directory of Open Access Journals (Sweden)

    Bing Huang

    2014-05-01

    Full Text Available Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single- and double-sided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high-efficiency, optoelectronic applications.

  20. A simulation study on the hydrogen storage properties of fullerene family molecules Cx(x = 56,60,70) and their hydrides

    Science.gov (United States)

    Dai, Wei; Xiao, Ming; Chen, Mu-Qing; Xu, Jia-Jing; Tang, Yong-Jian

    2016-08-01

    Hydrogen storage is a key factor for the application of hydrogen energy. From first principle calculation, we have acquired the energy barrier for hydrogen molecules to pass through the hexagonal rings and pentagonal rings of the fullerene. Then the absorption energy and energy barrier are used to analyze the hydrogen adsorption capacity of the fullerene family and their hydrides. We have also studied the hydrogen storage properties of the fullerene family and their hydrides by grand canonical Monte Carlo method. It is found that the weight density of hydrogen storage at ambient temperature and pressure can reach 7.71 wt.%. The results show that it is difficult for hydrogen to get into the carbon cage of the fullerene because of the high energy barrier, while it is beneficial to destroy the fullerene structure for the processes of absorption and desorption. Meanwhile, fullerene hydrogenation is an effective method to improve the hydrogen storage properties. Our study facilitates the design and synthesis of hydrogen storage materials, and provides theoretical support to improve the hydrogen storage capability for materials.

  1. Thermochemical properties of the hydrogen getter DEB

    Energy Technology Data Exchange (ETDEWEB)

    Balooch, M.; LeMay, J.D. [Lawrence Livermore National Lab., CA (United States); Wang, W.-E. [Department of Nuclear Engineering, 4164 Etcheverry Hall, University of California, Berkeley, CA 94720-1730 (United States)

    1999-04-20

    Vapor pressures of the hydrogen getter 1,4 bis(phenylethynyl)benzene (DEB), together with two of its derivatives namely DEB mixed with carbon-supported Pd (DEB-Pd/C) and hydrogenated DEB-Pd/C, are measured from room temperature to the melting temperature (179 C). The corresponding thermodynamic information, such as the enthalpy of vaporization, boiling point, and the deviation from ideal solution behavior of DEB-Pd/C, has been derived from the vapor pressure-temperature relationships. In addition, the hydrogenation kinetics of DEB-Pd/C (powder form and rod-like) has also been investigated at a fixed pressure of 13.3 Pa (0.1 Torr) and at four temperatures, 21 C, 35 C, 45 C and 55 C. (orig.) 5 refs.

  2. Hydrogenated dilute nitride semiconductors theory, properties, and applications

    CERN Document Server

    Ciatto, Gianluca

    2015-01-01

    ""The electrical and optical properties of the technologically and scientifically important dilute nitride semiconductors are strongly influenced by the introduction of atomic hydrogen. This volume is an excellent summary and resource for the most recent understanding of experimental results and state-of-the-art theoretical studies of the formation, reversibility, and microscopic structure of nitrogen-hydrogen complexes in these materials. The book details how a wide variety of experimental techniques have provided a detailed understanding of the role of hydrogen. It is the premier sourc

  3. Experimental and theoretical investigation of Fe-catalysis phenomenon in hydrogen thermal desorption from hydrocarbon plasma-discharge films from T-10 tokama

    Science.gov (United States)

    Stankevich, Vladimir G.; Sukhanov, Leonid P.; Svechnikov, Nicolay Yu.; Lebedev, Alexey M.; Menshikov, Kostantin A.; Kolbasov, Boris N.

    2017-10-01

    Investigations of the effect of Fe impurities on D2 thermal desorption (TD) from homogeneous CDx films (x ˜ 0.5) formed in the D-plasma discharge of the T-10 tokamak were carried out. The experimental TD spectra of the films showed two groups of peaks at 650-850 K and 900-1000 K for two adsorption states. The main result of the iron catalysis effect consists in the shift of the high-temperature peak by -24 K and in the increase in the fraction of the weakly bonded adsorption states. To describe the effect of iron impurities on TD of hydrogen isotopes, a structural cluster model based on the interaction of the Fe+ ion with the 1,3-C6H8 molecule was proposed. The potential energy surfaces of chemical reactions with the H2 elimination were calculated using ab initio methods of quantum chemistry. It was established that the activation barrier of hydrogen TD is reduced by about 1 eV due to the interaction of the Fe+ ion with the π-subsystem of the 1,3-C6H8 molecule leading to a redistribution of the double bonds along the carbon system. Contribution to the topical issue "Plasma Sources and Plasma Processes (PSPP)"", edited by Luis Lemos Alves, Thierry Belmonte and Tiberiu Minea

  4. Mg/Ti multilayers : Structural and hydrogen absorption properties

    NARCIS (Netherlands)

    Baldi, A.; Palsson, G. K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.; Rector, J. H.; Krishnan, G.; Kooi, B. J.; Walker, G. S.; Fay, M. W.; Hjorvarsson, B.; Wijngaarden, R. J.; Dam, B.; Griessen, R.; Hjörvarsson, B.

    2010-01-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a "spinodal-like" microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti

  5. Mg/Ti multilayers: Structural and hydrogen absorption properties

    NARCIS (Netherlands)

    Wijngaarden, R.J.; Baldi, A.; Pálsson, G. K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.J.; Rector, J.H.; Krishnan, G.; Kooi, B.J.; Walker, G. S.; Fay, M. W.; Hjörvarsson, B.; Dam, B.; Griessen, R.P.

    2010-01-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a "spinodal-like" microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti

  6. Mg/Ti multilayers : Structural and hydrogen absorption properties

    NARCIS (Netherlands)

    Baldi, A.; Pálsson, G.K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.; Rector, J.H.; Krishnan, G.; Kooi, B.J.; Walker, G.S.; Fay, M.W.; Hjörvarsson, B.; Wijngaarden, R.J.; Dam, B.; Griessen, R.

    2010-01-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a “spinodal-like” microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti

  7. Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4 Hydrogen Storage Composite.

    Science.gov (United States)

    Pei, Ziwei; Bai, Ying; Wang, Yue; Wu, Feng; Wu, Chuan

    2017-09-20

    The lightweight compound material NaNH2-NaBH4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH2-NaBH4 (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H2, NH3, B2H6, and N2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B6H12 also exists. The TG/DTA analyses show that the composite NaNH2-NaBH4 (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na3(NH2)2BH4 hydride decomposes into Na3BN2 and H2 (200-350 °C); (2) remaining Na3(NH2)2BH4 reacts with NaBH4 and Na3BN2, generating Na, BN, NH3, N2, and H2 (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.

  8. Moisture absorption/desorption effects on flexural property of Glass-fiber-reinforced polyester laminates : Three-point bending test and coupled hygro-mechanical finite element analysis

    NARCIS (Netherlands)

    Jiang, X.; Song, Jie; Qiang, X.; Kolstein, M.H.; Bijlaard, F.S.K.

    2016-01-01

    Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP) laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test

  9. Moisture Absorption/Desorption Effects on Flexural Property of Glass-Fiber-Reinforced Polyester Laminates: Three-Point Bending Test and Coupled Hygro-Mechanical Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2016-08-01

    Full Text Available Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A. The flexural properties of dry (0% Mt/M∞, moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞ and moisture saturated (100% Mt/M∞ specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0% and flexural strength (16.4% for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.

  10. First principle calculations for improving desorption temperature in ...

    Indian Academy of Sciences (India)

    ... we predict the improvement of the desorption temperature and the hydrogen storage properties of doped Mg-based hydrides such as,Mg15AMH32 (AM = Ca, Sr and Ba) as a super cell 2 × 2 × 2 of MgH2. In particular, the electronic structure has been obtained numerically using the all-electron full-potential local-orbital ...

  11. Shape-dependent hydrogen-storage properties in Pd nanocrystals: which does hydrogen prefer, octahedron (111) or cube (100)?

    Science.gov (United States)

    Li, Guangqin; Kobayashi, Hirokazu; Dekura, Shun; Ikeda, Ryuichi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki; Yamamoto, Tomokazu; Matsumura, Syo; Kitagawa, Hiroshi

    2014-07-23

    Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state (2)H NMR and hydrogen pressure-composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state (2)H NMR detected for the first time the state of (2)H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.

  12. Effect of acidic properties of mesoporous zeolites supporting pt nanoparticles on hydrogenative conversion of methylcyclopentane.

    Science.gov (United States)

    Na, Kyungsu; Alayoglu, Selim; Ye, Rong; Somorjai, Gabor A

    2014-12-10

    The effect of acidic properties of mesoporous zeolites on the control of product selectivity during the hydrogenative isomerization of methylcyclopentane has been investigated. A series of mesoporous zeolites with controlled acidic properties were prepared by postdealumination process with hydrochloric acid under hydrothermal conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs) with a mean size of 2.5 nm (± 0.6 nm). As compared to the pure Pt NPs supported on catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce isomers most selectively (∼80%), the Pt NPs supported on mesoporous zeolites produced C6-cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Brönsted (B) and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of pyridine and NH3 temperature-programmed desorption measurements, and they are correlated with the selectivity change between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Brönsted acid sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L ratio is effective for the cyclohexane formation, whereas more Brönsted acidic zeolite having relatively larger B/L ratio is effective for the benzene formation.

  13. Electronic and magnetic properties of pristine and hydrogenated borophene nanoribbons

    Science.gov (United States)

    Meng, Fanchen; Chen, Xiangnan; Sun, Songsong; He, Jian

    2017-07-01

    The groundbreaking works in graphene and graphene nanoribbons (GNRs) over the past decade, and the very recent discovery of borophene naturally draw attention to the yet-to-be-explored borophene nanoribbons (BNRs). We herein report a density functional theory (DFT) study of the electronic and magnetic properties of BNRs. The foci are the impact of orientation (denoted as BxNRs and ByNRs with their respective periodic orientations along x- and y-axis), ribbon width (Nx, Ny=4-15), and hydrogenation effects on the geometric, electronic and magnetic properties of BNRs. We found that the anisotropic quasi-planar geometric structure of BNR and the edge states largely govern its electronic and magnetic properties. In particular, pristine ByNRs adopt a magnetic ground state, either anti-ferromagnetic (AFM) or ferromagnetic (FM) depending on the ribbon width, while pristine BxNRs are non-magnetic (NM). Upon hydrogenation, all BNRs exhibit NM. Interestingly, both pristine and hydrogenated ByNRs undergo a metal-semiconductor-metal transition at Ny=7, while all BxNRs remain metallic.

  14. Electrocatalytic activity of a mononuclear yttrium(III)–methyl orange complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles for adsorption/desorption of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Shafaie, Fahimeh [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Hadadzadeh, Hassan, E-mail: hadad@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Behnamfar, Mohammad Taghi [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Rudbari, Hadi Amiri [Faculty of Chemistry, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of)

    2016-12-01

    A new mononuclear yttrium(III) complex, [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}] (where MO{sup –} is methyl orange anion (4-[(4-dimethylamino)phenyldiazenyl]benzenesulfonate)), was synthesized in an aqueous solution. The complex was characterized by elemental analysis, UV/Vis, FT-IR, and single-crystal X-ray crystallography. The yttrium oxysulfate nanoparticles (Y{sub 2}O{sub 2}SO{sub 4}) were then prepared by calcination of [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}]. The obtained nanoparticles were characterized by FT-IR, X-ray diffraction analysis (XRD), and field-emission scanning electron microscopy (FE-SEM). The hydrogen adsorption/desorption (H{sub ads}/H{sub des}) behavior of the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles was studied at a carbon paste electrode (CPE) in H{sub 2}SO{sub 4} by cyclic voltammetry (CV). The recorded voltammograms exhibited a pair of peaks corresponding to the adsorption/desorption of hydrogen for the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. The results show a reversible hydrogen adsorption/desorption reaction for both compounds. The voltammograms of the nanoparticles indicate an excellent cycling stability for the adsorption/desorption of hydrogen. In addition, the linear sweep voltammetry (LSV) technique was used to investigate the electrocatalytic activity of both compounds for the hydrogen adsorption reaction. The linear voltammograms of both compounds demonstrate the excellent electrocatalytic activity for the hydrogen adsorption reaction. - Highlights: • Preparation of a new Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. • Investigation of the H{sub ads}/H{sub des} reaction for both compounds by voltammetry. • Observation of two peaks corresponding to the H{sub ads}/H{sub des} in both compounds. • An excellent cycling stability for the nanoparticles in H{sub 2}SO{sub 4}.

  15. Synthesis of small metallic Mg-based nanoparticles confined in porous carbon materials for hydrogen sorption.

    Science.gov (United States)

    Zlotea, Claudia; Chevalier-César, Clotaire; Léonel, Eric; Leroy, Eric; Cuevas, Fermin; Dibandjo, Philippe; Vix-Guterl, Cathie; Martens, Thierry; Latroche, Michel

    2011-01-01

    MgH2, Mg-Ni-H and Mg-Fe-H nanoparticles inserted into ordered mesoporous carbon templates have been synthesized by decomposition of organometallic precursors under hydrogen atmosphere and mild temperature conditions. The hydrogen desorption properties of the MgH2 nanoparticles are studied by thermo-desorption spectroscopy. The particle size distribution of MgH2, as determined by TEM, is crucial for understanding the desorption properties. The desorption kinetics are significantly improved by downsizing the particle size below 10 nm. Isothermal absorption/desorption cycling of the MgH2 nanoparticles shows a stable capacity over 13 cycles. The absorption kinetics are unchanged though the desorption kinetics are slower on cycling.

  16. Hydrogenation Properties of TiFe Doped with Zirconium

    Directory of Open Access Journals (Sweden)

    Catherine Gosselin

    2015-11-01

    Full Text Available The goal of this study was to optimize the activation behaviour of hydrogen storage alloy TiFe. We found that the addition of a small amount of Zr in TiFe alloy greatly reduces the hydrogenation activation time. Two different procedural synthesis methods were applied: co-melt, where the TiFe was melted and afterward re-melted with the addition of Zr, and single-melt, where Ti, Fe and Zr were melted together in one single operation. The co-melted sample absorbed hydrogen at its maximum capacity in less than three hours without any pre-treatment. The single-melted alloy absorbed its maximum capacity in less than seven hours, also without pre-treatment. The reason for discrepancies between co-melt and single-melt alloys was found to be the different microstructure. The effect of air exposure was also investigated. We found that the air-exposed samples had the same maximum capacity as the argon protected samples but with a slightly longer incubation time, which is probably due to the presence of a dense surface oxide layer. Scanning electron microscopy revealed the presence of a rich Zr intergranular phase in the TiFe matrix, which is responsible for the enhanced hydrogenation properties of these Zr-doped TiFe alloys.

  17. The Effects of Nanostructure on the Hydrogen Sorption Properties of Magnesium-Based Metallic Compounds: A Review

    Directory of Open Access Journals (Sweden)

    Luca Pasquini

    2018-02-01

    Full Text Available In this review, I examine the influence of nanoscale materials features on the hydrogen-metal interaction. The small system size, the abundance of surfaces/interfaces, and the spatial distribution of phases are the key factors to understand the hydrogen sorption properties of nanomaterials. In order to describe nanoscale-specific thermodynamic changes, I present a quantitative model applicable to every hydride-forming material, independently on its composition and atomic structure. The effects of surface free energy, interface free energy, and elastic constraint, are included in a general expression for the thermodynamical bias. In the frame of this model, I critically survey theoretical and experimental results hinting at possible changes of thermodynamic parameters, and in particular, enthalpy and entropy of hydride formation, in nanostructured Mg-based metallic compounds as compared to their coarse-grained bulk counterparts. I discuss the still open controversies, such as destabilization of ultra-small clusters and enthalpy–entropy compensation. I also highlight the frequently missed points in experiments and data interpretation, such as the importance of recording full hydrogen absorption and desorption isotherms and of measuring the hysteresis. Finally, I try to address the open questions that may inspire future research, with the ambition of tailoring the properties of hydride nanomaterials through a deeper understanding of their thermodynamics.

  18. Highly efficient bimetal synergetic catalysis by a multi-wall carbon nanotube supported palladium and nickel catalyst for the hydrogen storage of magnesium hydride.

    Science.gov (United States)

    Yuan, Jianguang; Zhu, Yunfeng; Li, Liquan

    2014-06-25

    A multi-wall carbon nanotube supported Pd and Ni catalyst efficiently catalyzes the hydrogen storage of magnesium hydride prepared by HCS + MM. Excellent hydrogen storage properties were obtained: hydrogen absorption - 6.44 wt% within 100 s at 373 K, hydrogen desorption - 6.41 wt% within 1800 s at 523 K and 6.70 wt% within 400 s at 573 K.

  19. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  20. Characterization of crude oil-water and solid -water interfaces and adsorption / desorption properties of crude oil fractions: The effect of low salinity water and pH

    Energy Technology Data Exchange (ETDEWEB)

    Farooq, Umer

    2010-09-15

    The reservoirs of conventional oil are rapidly depleting because of increased production and consumption of crude oil in the world. Mature and mostly depleted oil reservoirs require advanced recovery techniques to sustain the production rates. During the past years, a variety of enhanced oil recovery (EOR) methods have been developed and implemented to increase the oil recovery from mature reservoirs. Low Salinity Waterflooding (LSW) is an emerging EOR process of injecting water containing low concentrations (<4000 ppm) of total dissolved solids into the reservoir. This moderate cost process yields relatively higher incremental recoveries than other water based recovery methods. Investigation of mechanisms for increased recovery is quite challenging because this process depends upon complex crude oil/water/rock properties. This work was done to study the surface chemistry of typical reservoir surfaces where LSW can be used for EOR. The oil water and solid-water interfaces were characterised in low salinity aqueous solutions and investigated how the electrolytes and pH of solutions affect the interfacial and surface properties. The influence of low saline aqueous solution on the desorption behaviour of different fractions (acid-free oil and base-free oil) of crude oils was also explored. Reservoir minerals are sensitive to small changes in solution properties and therefore model, outcrop and reservoir particles were characterized in low salinity aqueous solutions. The extent of ionic adsorption on the mineral surfaces was found by various techniques. Particles were also characterized with respect to their elemental compositions. Asphaltene adsorption/desorption on reservoir rock surfaces play an important role in EOR processes. Various injection sequences of low saline aqueous solution of Na +, Ca2+ and sea water were considered to study the desorption of asphaltenes from silica surfaces. Composition of the aqueous phase influenced the interfacial properties of

  1. Desorption process of hydrogen starting from the Mg{sub 2}NiH{sub 4} and Mg{sub 2}NiH{sub 0.3}; Proceso de desorcion de hidrogeno a partir del hidruro intermetalico Mg{sub 2}NiH{sub 4} y Mg{sub 2}NiH{sub 0.3}

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe G, J.L.; Basurto S, R.; Lopez M, B.E. [Departamento de Quimica, ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    In this work the desorption velocity of H{sub 2} was determined starting from the magnesium nickel hydride once the reaction between the intermetallic and the hydrogen was realized, the compound were analysed by means of a thermogravimetric equipment, the conditions for carrying out the analysis were: 10 C by minute in nitrogen atmosphere at a volume of 50 ml by minute, subsequently the isotherms at different times were programmed and the desorption velocity of hydrogen was determined. The results show that the desorption velocity of hydrogen depends of the temperature, using only the nitrogen flux which acts as a carrier gas. Observing that the hydrogen liberation is carried out by means of two mechanisms according to the isotherms obtained. (Author)

  2. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  3. Transport properties of liquid metal hydrogen under high pressures

    Science.gov (United States)

    Brown, R. C.; March, N. H.

    1972-01-01

    A theory is developed for the compressibility and transport properties of liquid metallic hydrogen, near to its melting point and under high pressure. The interionic force law is assumed to be of the screened Coulomb type, because hydrogen has no core electrons. The random phase approximation is used to obtain the structure factor S(k) of the system in terms of the Fourier transform of this force law. The long wavelenth limit of the structure factor S(o) is related to the compressibility, which is much lower than that of alkali metals at their melting points. The diffusion constant at the melting point is obtained in terms of the Debye frequency, using a frequency spectrum analogous with the phonon spectrum of a solid. A similar argument is used to obtain the combined shear and bulk viscosities, but these depend also on S(o). The transport coefficients are found to be about the same size as those of alkali metals at their melting points.

  4. Two approaches for enhancing the hydrogenation properties of ...

    Indian Academy of Sciences (India)

    Wintec

    hydrogen loading and deloading cycles in both bimetallic systems. Alloying between .... deloading cycles. On hydrogen loading, resistance of bimetal layer increases by about 7⋅4%. This is be- cause Pd on interaction with hydrogen forms palla- dium hydride .... lytic interaction of Pd with H2 is significant. Cu and. Pd form ...

  5. Tailoring the Hydrogen Detection Properties of Metal Hydrides

    NARCIS (Netherlands)

    Boelsma, C.

    2017-01-01

    Hydrogen plays an essential role in many sectors of the industry. For example, hydrogen is necessary to produce ammonia, it can be used to determine the quality of products (hydrogen is produced during food ageing), or it can result in medical diagnostics (e.g. lactose intolerance). In addition,

  6. Hydrogen storing and electrical properties of hyperbranched polymers-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Rehim, Mona H., E-mail: monaabdelrehim@yahoo.com [Packing and Packaging Materials Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Ismail, Nahla; Badawy, Abd El-Rahman A.A. [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Turky, Gamal [Microwave Physics and Dielectrics Department, National Research Center, Cairo (Egypt)

    2011-09-15

    Highlights: {center_dot} The hydrogen storage capacity of hyperbranched P-Urea, PAMAM and PAMAM and VO{sub x} is studied and electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. {center_dot} Electrical properties measurements for the samples showed complete insulating behavior at hydrogenation measuring temperature. {center_dot} These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. - Abstract: Hydrogen storage and electrical properties of different hyperbranched polymer systems beside a nanocomposite are studied. The polymers examined are aliphatic hyperbranched poly urea (P-Urea), polyamide amine (PAMAM) and polyamide amine/vanadium oxide (PAMAM/VO{sub x}) nanocomposite. At 80 K and up to 20 bar hydrogen pressure, the hydrogen storage capacity of hyperbranched P-Urea reached 1.6 wt%, 0.9 wt% in case of PAMAM and 0.6 wt% for VO{sub x}. The hydrogen storage capacity significantly enhanced when PAMAM and VO{sub x} form a nanocomposite and increased up to 2 wt%. At 298 K and up to 20 bar, all the samples did not show measurable hydrogen uptake. Electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage.

  7. Recommended Best Practices for the Characterization of Storage Properties of Hydrogen Storage Materials

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-03-01

    This is a reference guide to common methodologies and protocols for measuring critical performance properties of advanced hydrogen storage materials. It helps users to communicate clearly the relevant performance properties of new materials as they are discovered and tested.

  8. Phase Transformation and Hydrogen Storage Properties of an La7.0Mg75.5Ni17.5 Hydrogen Storage Alloy

    Directory of Open Access Journals (Sweden)

    Lin Hu

    2017-10-01

    Full Text Available X-ray diffraction showed that an La7.0Mg75.5Ni17.5 alloy prepared via inductive melting was composed of an La2Mg17 phase, an LaMg2Ni phase, and an Mg2Ni phase. After the first hydrogen absorption/desorption process, the phases of the alloy turned into an La–H phase, an Mg phase, and an Mg2Ni phase. The enthalpy and entropy derived from the van’t Hoff equation for hydriding were −42.30 kJ·mol−1 and −69.76 J·K−1·mol−1, respectively. The hydride formed in the absorption step was less stable than MgH2 (−74.50 kJ·mol−1 and −132.3 J·K−1·mol−1 and Mg2NiH4 (−64.50 kJ·mol−1 and −123.1 J·K−1·mol−1. Differential thermal analysis showed that the initial hydrogen desorption temperature of its hydride was 531 K. Compared to Mg and Mg2Ni, La7.0Mg75.5Ni17.5 is a promising hydrogen storage material that demonstrates fast adsorption/desorption kinetics as a result of the formation of an La–H compound and the synergetic effect of multiphase.

  9. Electonic properties of hydrogenated amorphous silicon-germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bullot, J.; Galin, M.; Gauthier, M. (Universite de Paris-Sud, Orsay (France)); Bourdon, B. (CIT-Alcatel Transmission, Marcoussis (France))

    1983-06-01

    The electronic properties of some binary hydrogenated amorphous silicon-germanium alloys a-Sisub(x)Gesub(1-x):H in the silicon rich region (x > 0.6) are investigated. Experimental evidence is presented of photo-induced effects similar to those described in Si:H (Staebler-Wronski effect). The electronic properties are then studied from the dual point of view of the germanium content dependence and of the photo and thermal histories of the films. The dark conductivity changes between the annealed state and the light-soaked state are interpreted in terms of the variation of the temperature coefficient of the Fermi level. The photoconductivity efficiency is shown to remain close to that of a-Si:H for 1 > x >= 0.9 and to strongly decrease when the germanium content is further increased: the photoresponse of the Sisub(0.62)Gesub(0.38) alloy is 10/sup 4/ times smaller than that of a-Si:H. This deterioration of the photoconductive properties is explained in terms of the increase of the density of gap states following Ge substitution. This conclusion is based on the study of the width of the exponential absorption edge and on the results of photoconductivity time response studies. The latter data are interpreted by means of the model of Rose of trapping and recombination kinetics and it is found that for x approximately 0.6 the density of states at 0.4-0.5 eV below the mobility edge is 7 x 10/sup 17/ eV/sup -1/ cm/sup -3/ as compared to 2.4 x 10/sup 16/ eV/sup -1/ cm/sup -3/ for x = 0.97.

  10. Effect of Strain-Induced Martensite on Tensile Properties and Hydrogen Embrittlement of 304 Stainless Steel

    Science.gov (United States)

    Kim, Young Suk; Bak, Sang Hwan; Kim, Sung Soo

    2016-01-01

    Room temperature tensile tests have been conducted at different strain rates ranging from 2 × 10-6 to 1 × 10-2/s on hydrogen-free and hydrogen-charged 304 stainless steel (SS). Using a ferritescope and neutron diffraction, the amount of strain-induced martensite (SIM) has been in situ measured at the center region of the gage section of the tensile specimens or ex situ measured on the fractured tensile specimens. The ductility, tensile stress, hardness, and the amount of SIM increase with decreasing strain rate in hydrogen-free 304 SS and decrease in hydrogen-charged one. Specifically, SIM that forms during tensile tests is beneficial in increasing the ductility, strain hardening, and tensile stress of 304 SS, irrespective of the presence of hydrogen. A correlation of the tensile properties of hydrogen-free and hydrogen-charged 304 SS and the amount of SIM shows that hydrogen suppresses the formation of SIM in hydrogen-charged 304 SS, leading to a ductility loss and localized brittle fracture. Consequently, we demonstrate that hydrogen embrittlement of 304 SS is related to hydrogen-suppressed formation of SIM, corresponding to the disordered phase, according to our proposition. Compelling evidence is provided by the observations of the increased lattice expansion of martensite with decreasing strain rate in hydrogen-free 304 SS and its lattice contraction in hydrogen-charged one.

  11. Properties of Mg-Al alloys in relation to hydrogen storage

    DEFF Research Database (Denmark)

    Andreasen, A.

    2005-01-01

    Magnesium theoretically stores 7.6 wt. % hydrogen, although it requires heating to above 300 degrees C in order to release hydrogen. This limits its use for mobile application. However, due to its low price and abundance magnesium should still beconsidered as a potential candidate for hydrogen...... storage e.g. in stationary applications. In this report the properties of Mg-Al alloys are reviewed in relation to solid state hydrogen storage. Alloying with Al reduces the hydrogen capacity since Al doesnot form a hydride under conventional hydriding conditions, however both the thermodynamical...

  12. Study of properties of tungsten irradiated in hydrogen atmosphere

    Science.gov (United States)

    Tazhibayeva, I.; Skakov, M.; Baklanov, V.; Koyanbayev, E.; Miniyazov, A.; Kulsartov, T.; Ponkratov, Yu.; Gordienko, Yu.; Zaurbekova, Zh.; Kukushkin, I.; Nesterov, E.

    2017-12-01

    The paper presents the results of the experiments with DF (double forged) tungsten samples irradiated at the WWR-K research reactor in hydrogen and helium atmospheres. The irradiation time was 3255 h (135.6 d). After reactor irradiation, W samples have been subjected to investigations of their activity level, hardness, and microstructure, as well as x-ray and texture observations. The hydrogen yield released from irradiated tungsten samples have been measured using TDS-method. The hydrogen concentration in the tungsten samples irradiated in hydrogen was higher than that in the samples irradiated in helium atmosphere. It is shown that the surface microstructure of tungsten samples irradiated in hydrogen is characterized by micro-pits, inclusions and blisters in the form of bubbles, which were not observed earlier for tungsten irradiated in hydrogen.

  13. Effects of hydrogen upon the properties of thermo mechanical controlled process (TMCP steel

    Directory of Open Access Journals (Sweden)

    T. Tomić

    2016-01-01

    Full Text Available Research into the effects of hydrogen on the mechanical properties of the material is wide-ranging and time-consuming, since there is no single way of predicting cold cracking that would be applicable to all steel grades. Some research on the action of hydrogen in the weld area has focused on the effects of filler materials, welding parameters, the welding environment and welding process upon the hydrogen content of the weld metal and final effect of the hydrogen content upon the properties of the material.

  14. Some properties of solid helium and helium nanoclusters using the effective HFD-like interaction potential: Adsorption and desorption inside carbon nanotube

    Science.gov (United States)

    Abbaspour, M.; Akbarzadeh, H.; Banihashemi, S. Z.; Sotoudeh, A.

    2018-02-01

    We have calculated the zero equation of state of solid helium using a two-body Hartree-Fock dispersion (HFD)-like potential from molecular dynamics (MD) simulation. To take many-body forces into account, our simple and accurate empirical expression is used with the HFD-like potential without requiring an expensive three-body calculation. This potential model also includes the quantum effects for helium at low temperatures. The results indicate that our effective HFD-like potential improves the prediction of the classical two-body results to get better agreement with experiment than many other two-body and three-body potentials of helium reported in the literature. We have also simulated the adsorption and desorption processes of the (He)55, (He)147, (He)309, (He)561, and (He)923 icosahedral nanoclusters confined into the different armchair and zigzag CNTs from 0 to 50 K using our effective model. We have observed an interesting phenomenon at 0 K for helium. The nanoclusters adsorb to the inner CNT wall as a melting process. But, the heavier noble gas clusters (such as Ne and Xe) show the different behavior than the He clusters. They form a multilayered solid structure into the CNT at zero temperature and adsorb into the inner wall of the CNT at higher temperatures. Our results for He clusters show that the absolute value of the adsorption energy increases as the size of the nanocluster increases. The desorption process begins at a certain temperature and represents itself by a jump in the configurational energy values. We have also investigated the structural and dynamical properties of the confined helium nanoclusters during the adsorption and desorption processes at different temperatures.

  15. Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect; Catalyseurs de nickel supportes prepares par la methode de l'hydrazine aqueuse. Proprietes hydrogenantes et stockage d'hydrogene. Effet du support. Effet de l'ajout d'argent

    Energy Technology Data Exchange (ETDEWEB)

    Wojcieszak, R

    2006-06-15

    We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports ({gamma}-Al{sub 2}O{sub 3}, amorphous or crystallized SiO{sub 2}, Nb{sub 2}O{sub 5}, CeO{sub 2} and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N{sub 2}, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H{sub 2}-TPR, H{sub 2}-adsorption, H{sub 2}-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO{sub 2} or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

  16. Temperature Programmed Desorption and Infrared Spectroscopic Studies of Interfacial Hydrogen Bonds for Small Molecules Adsorbed on Silica and Within Metal Organic Frameworks

    OpenAIRE

    Abelard, Joshua Erold Robert

    2017-01-01

    Hydrogen bonds are arguably the most important reversible intermolecular forces. However, surprisingly few studies of their fundamental nature at the gas-surface interface have been performed. Our research investigated sulfur mustard (HD) adsorption by characterizing interfacial hydrogen bonding and dispersion forces for the simulant molecules 2-chloroethyl ethyl sulfide (2-CEES) and methyl salicylate on well-characterized hydroxyl-functionalized surfaces (silica and UiO-66). Our approach uti...

  17. MICROSTRUCTURE AND MECHANICAL PROPERTY PERFORMANCE OF COMMERCIAL GRADE API PIPELINE STEELS IN HIGH PRESSURE GASEOUS HYDROGEN

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Mr. Douglas [DGS Metallurgical Solutions Inc; Boggess, Todd [Secat; San Marchi, Chris [Sandia National Laboratories (SNL); Jansto, Steven [Reference Metals Company; Somerday, Dr. B [Sandia National Laboratories (SNL); Muralidharan, Govindarajan [ORNL; Sofronis, Prof. Petros [University of Illinois

    2010-01-01

    The continued growth of the world s developing countries has placed an ever increasing demand on traditional fossil fuel energy sources. This development has lead to increasing research and development of alternative energy sources. Hydrogen gas is one of the potential alternative energy sources under development. Currently the most economical method of transporting large quantities of hydrogen gas is through steel pipelines. It is well known that hydrogen embrittlement has the potential to degrade steel s mechanical properties when hydrogen migrates into the steel matrix. Consequently, the current pipeline infrastructure used in hydrogen transport is typically operated in a conservative fashion. This operational practice is not conducive to economical movement of significant volumes of hydrogen gas as an alternative to fossil fuels. The degradation of the mechanical properties of steels in hydrogen service is known to depend on the microstructure of the steel. Understanding the levels of mechanical property degradation of a given microstructure when exposed to hydrogen gas under pressure can be used to evaluate the suitability of the existing pipeline infrastructure for hydrogen service and guide alloy and microstructure design for new hydrogen pipeline infrastructure. To this end, the 2 Copyright 2010 by ASME microstructures of relevant steels and their mechanical properties in relevant gaseous hydrogen environments must be fully characterized to establish suitability for transporting hydrogen. A project to evaluate four commercially available pipeline steels alloy/microstructure performance in the presences of gaseous hydrogen has been funded by the US Department of Energy along with the private sector. The microstructures of four pipeline steels were characterized and then tensile testing was conducted in gaseous hydrogen and helium at pressures of 800, 1600 and 3000 psi. Based on measurements of reduction of area, two of the four steels that performed the best

  18. Reconstruction of negative hydrogen ion beam properties from beamline diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ruf, Benjamin

    2014-09-25

    For the experimental fusion reactor ITER, which should show the feasibility of sustaining a fusion plasma with a positive power balance, some technology still has to be developed, amongst others also the plasma heating system. One heating technique is the neutral beam injection (NBI). A beam of fast deuterium atoms is injected into the fusion plasma. By heavy particle collisions the beam particles give their energy to the plasma. A NBI system consists of three major components. First, deuterium ions are generated in a low temperature, low pressure plasma of an ion source. At ITER, the requirements on the beam energy of 1 MeV cause the necessity of negative charged deuterium ions. Secondly, the ions are accelerated within an acceleration system with several grids, where the plasma grid is the first grid. The grids are on different descending high voltage potentials. The source itself is on the highest negative potential. Thirdly, the fast deuterium ions have to be neutralised. This thesis deals with the second step in the mentioned beam system, the ion acceleration and beam formation. The underlying experiments and measurements were carried out at the testbeds BATMAN (BAvarianTest MAchine for Negative ions) and ELISE (Extraction from a Large Ion Source Experiment) at the Max-Planck-Institut fuer Plasmaphysik Garching (IPP Garching). The main goal of this thesis is to provide a tool which allows the determination of the beam properties. These are beam divergence, stripping losses and beam inhomogeneity. For this purpose a particle trajectory code has been developed from scratch, namely BBC-NI (Bavarian Beam Code for Negative Ions). The code is able to simulate the whole beam and the outcome of several beam diagnostic tools. The data obtained from the code together with the measurements of the beam diagnostic tools should allow the reconstruction of the beam properties. The major beam diagnostic tool, which is used in this thesis, is the beam emission spectroscopy

  19. Experimental study of the combustion properties of methane/hydrogen mixtures

    NARCIS (Netherlands)

    Gersen, Sander

    2007-01-01

    In this thesis the combustion properties of methane / hydrogen mixtures are investigated by measering autoignition delay times in methane/hydrogen mixtures under conditions relevant for gasengines. Moreover HCN and C2H2 measurements have been performed in fuel-rich one dimensional laminar CH4/H2/air

  20. Suppressing diborane production during the hydrogen release of metal borohydrides: The example of alloyed Al(BH$_4$)$_3$

    OpenAIRE

    Harrison, D.; Thonhauser, T.

    2016-01-01

    Aluminum borohydride (Al(BH$_4$)$_3$) is an example of a promising hydrogen storage material with exceptional hydrogen densities by weight and volume and a low hydrogen desorption temperature. But, unfortunately, its production of diborane (B$_2$H$_6$) gases upon heating to release the hydrogen restricts its practical use. To elucidate this issue, we investigate the properties of a number of metal borohydrides with the same problem and find that the electronegativity of the metal cation is no...

  1. Preparation and properties of hydrogen storage alloy-copper microcapsules

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, H.; Oguro, K.; Kato, A.; Suzuki, H.; Ishii, E.

    1985-05-01

    Fine particles of hydrogen storage alloys such as LaNi/sub 5/ and MmNisub(4.5)-Mnsub(0.5) (Mm = misch metal) were encapsulated in a thin layer of copper 1-2 ..mu..m thick by means of a special chemical plating method. This treatment prevented further disintegration of the metal and improved the thermal conductivity. The alloy-copper microcapsules, which had dimensions of less than 30 ..mu..m, were able to absorb hydrogen easily without special activation and exhibited no decrease in hydrogen storage capacity. Pellets obtained by compressing the microencapsulated powder under a pressure of 5-10 tf cm/sup -2/ did not show any visible cracks after 1000 hydrogen sorption cycles.

  2. Nanocrystalline magnesium and its properties of hydrogen sorption

    OpenAIRE

    David, E.

    2007-01-01

    Purpose: The goal of this paper is to study the possibility of obtaining of magnesium and magnesium hydride innanocrystallyne form and then to activate these materials for to be used in efficient systems of hydrogen storage.Design/methodology/approach: The magnesium hydride (MgH2 ) was directly synthesised from mechanicallygrinded magnesium powder obtained through ball milling of Mg (BM), and hydrogen of high purity. The MgH2was then chemical activation by surface modification of nanocrystall...

  3. Properties of SBA-15 modified by iron nanoparticles as potential hydrogen adsorbents and sensors

    Science.gov (United States)

    Bouazizi, N.; Ouargli, R.; Nousir, S.; Slama, R. Ben; Azzouz, A.

    2015-02-01

    SBA-15-Fe was synthesized via the incorporation of Fe0 nanoparticles (Fe(0)-Nps) in the mesoporous channels. Electron microscopy and X-ray diffraction showed that dispersion of fine iron NPs occurs mainly inside the channels of SBA-15, producing a slight structure compaction. This was accompanied by a significant improvement of both the affinity towards hydrogen and electrical conductivity, as supported by hydrogen adsorption tests and impedance measurements. CO2 thermal programmed desorption measurements revealed an attenuation of the acid character of the solid surface. This was explained in terms of strong iron interaction with the lattice oxygen atoms that reduces the SiO-H bond polarity. The close vicinity of fine Fe(0)-Nps combined with the large pore size of SBA-15 appear to contribute to a synergistic improvement of the electrical conductivity. The results reported herein open new prospects for SBA-15 as potential adsorbents for hydrogen storage and carriers for hydrogen sensors. The use of iron in lieu of noble metals for designing such materials is a novelty, because such applications of iron-loaded silica have not been envisaged so far due to the high reactivity of iron towards air and water. The development of such technologies, if any, should address this issue.

  4. Tunable electronic structures and magnetic properties in two-dimensional stanene with hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Sheng-shi; Zhang, Chang-wen, E-mail: zhchwsd@163.com

    2016-04-15

    Based on tight-binding model and first-principles calculations, we systematically investigate the geometric, electronic, and magnetic properties of hydrogenated stanene. The results indicate that the half-hydrogenation breaks the π-bondings of stanene, leaving π electrons in unsaturated Sn atoms localized and unpaired, which makes it transform into half-metal (HM) with room-temperature ferromagnetism. Especially, the magnetism of hydrogenated stanene can be effectively tuned by different rates of coverage for hydrogen atoms. While for the case of full-hydrogenated stanene, two different configurations exhibit the nature of semiconductor and semimetal, respectively, which is dependent on the arrangement of hydrogen atoms. We also find that the band gaps of stanane bilayer and monolayer can be effectively modulated by external electric field and strain. These findings demonstrate that hydrogenation is an efficient way to tune the electronic properties of stanene, and it provides a new perspective for the potential application in nanoelectronics. - Highlights: • Room temperature ferromagnetism in half hydrogenated stanene. • The effects of the ratio of hydrogenation and electric field. • Tunable band gaps of stanane by external factor.

  5. Study on glass-forming ability and hydrogen storage properties of amorphous Mg{sub 60}Ni{sub 30}La{sub 10−x}Co{sub x} (x = 0, 4) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Peng; Wang, Zhong-min, E-mail: zmwang@guet.edu.cn; Zhang, Huai-gang; Balogun, Muhammad-Sadeeq; Ji, Zi-jun; Deng, Jian-qiu; Zhou, Huai-ying

    2013-12-15

    Mg{sub 60}Ni{sub 30}La{sub 10−x}Co{sub x} (x = 0, 4) amorphous alloys were prepared by rapid solidification, using a melt-spinning technique. X-ray diffraction and differential scanning calorimetry analysis were employed to measure their microstructure, thermal stability and glass-forming ability, and hydrogen storage properties were studied by means of PCTPro2000. Based on differential scanning calorimetry results, their glass-forming ability and thermal stability were investigated by Kissinger method, Lasocka curves and atomic cluster model, respectively. The results indicate that glass-forming ability, thermal properties and hydrogen storage properties in the Mg-rich corner of Mg–Ni–La–Co system alloys were enhanced by Co substitution for La. It can be found that the smaller activation energy (ΔΕ) and frequency factor (υ{sub 0}), the bigger value of B (glass transition point in Lasocka curves), and higher glass-forming ability of Mg–Ni–La–Co alloys would be followed. In addition, atomic structure parameter (λ), deduced from atomic cluster model is valuable in the design of Mg–Ni–La–Co system alloys with good glass-forming ability. With an increase of Co content from 0 to 4, the hydrogen desorption capacity within 4000 s rises from 2.25 to 2.85 wt.% at 573 K. - Highlights: • Amorphous Mg{sub 60}Ni{sub 30}La{sub 10−x}Co{sub x} (x = 0 and 4) alloys were produced by melt spinning. • The GFA and hydrogen storage properties were enhanced by Co substitution for La. • With an increase of Co content, the hydrogen desorption capacity rises at 573 K.

  6. Hydrogen storage thermodynamics and kinetics of LaMg{sub 11}Ni + x wt.% Ni (x = 100, 200) alloys synthesized by mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanghuan; Jia, Zhichao [Inner Mongolia Univ. of Science and Technology, Baotou (China). Key Lab. of Integrated Exploitation of Baiyun Obo Multi-Metal Resources; Central Iron and Steel Research Institute, Beijing (China). Dept. of Functional Material Research; Yuan, Zeming; Qi, Yan; Zhao, Dongliang [Central Iron and Steel Research Institute, Beijing (China). Dept. of Functional Material Research; Hou, Zhonghui [Inner Mongolia Univ. of Science and Technology, Baotou (China). Key Lab. of Integrated Exploitation of Baiyun Obo Multi-Metal Resources

    2016-04-15

    LaMg{sub 11}Ni + x wt.% Ni (x = 100, 200) composite hydrogen storage alloys with a nanocrystalline/amorphous structure were synthesized using ball milling technology. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were investigated systematically. The hydrogen desorption properties were assessed using a Sieverts apparatus and differential scanning calorimetry. The thermodynamic parameters for the hydrogen absorption and desorption were calculated using the Van't Hoff equation. The hydrogen desorption activation energies of the hydrogenated alloys were also estimated by Arrhenius and Kissinger methods. Results indicate that the amount of Ni added has no effect on the thermodynamics of the alloys, but it significantly improves their absorption and desorption kinetics. Furthermore, the milling time has a great influence on the hydrogen storage properties. To be specific, the hydrogen absorption capacities reach the maximum values with the variation of milling time, and the hydrogen desorption activation energy obviously decreases with increasing milling time.

  7. Dosimeter-Type NOx Sensing Properties of KMnO4 and Its Electrical Conductivity during Temperature Programmed Desorption

    Directory of Open Access Journals (Sweden)

    Ralf Moos

    2013-04-01

    Full Text Available An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT for NOx storage catalysts (NSC enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD. The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1 time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2 during the short-term thermal NOx release.

  8. Dosimeter-Type NOx Sensing Properties of KMnO4 and Its Electrical Conductivity during Temperature Programmed Desorption

    Science.gov (United States)

    Groβ, Andrea; Kremling, Michael; Marr, Isabella; Kubinski, David J.; Visser, Jacobus H.; Tuller, Harry L.; Moos, Ralf

    2013-01-01

    An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release. PMID:23549366

  9. Fabrication of Nickel Nanotube Using Anodic Oxidation and Electrochemical Deposition Technologies and Its Hydrogen Storage Property

    Directory of Open Access Journals (Sweden)

    Yan Lv

    2016-01-01

    Full Text Available Electrochemical deposition technique was utilized to fabricate nickel nanotubes with the assistance of AAO templates. The topography and element component of the nickel nanotubes were characterized by TEM and EDS. Furthermore, the nickel nanotube was made into microelectrode and its electrochemical hydrogen storage property was studied using cyclic voltammetry. The results showed that the diameter of nickel nanotubes fabricated was around 20–100 mm, and the length of the nanotube could reach micron grade. The nickel nanotubes had hydrogen storage property, and the hydrogen storage performance was higher than that of nickel powder.

  10. Crystal Properties and Radiation Effects in Solid Molecular Hydrogens

    Energy Technology Data Exchange (ETDEWEB)

    Kozioiziemski, B

    2000-09-01

    The crystal lattice structure, growth shapes and helium generated by beta-decay of solid deuterium-tritium (D-T) mixtures have been studied. Understanding of these D-T properties is important for predicting and optimizing the target design of the National Ignition Facility (NIF). Raman spectroscopy showed the D-T crystal structure is hexagonal close packed, common to the non-tritiated isotopes. The isotopic mixtures of both tritiated and non-tritiated species broadens the rotational transitions, especially of the lighter species in the mixture. The vibrational frequencies of each isotope is shifted to higher energy in the mixture than the pure components. The J = 1-0 population decreases exponentially with a 1/e time constant which rapidly increases above 10.5 K for both D{sub 2} and T{sub 2} in D-T. The conversion rate is nearly constant from 5 K to 10 K for both D{sub 2} and T{sub 2} at 7.1 hours and 2.1 hours, respectively. The smoothing of D-T layers by beta decay heating is limited by the crystal surface energy. Deuterium and hydrogen-deuteride crystals were grown at a number of temperatures below the triple point to determine the surface energy and roughening transition. Several distinct crystal shapes were observed on a number of different substrates. The a facet roughens between 0.9 T{sub TP} and T{sub TP}, while the c facet persists up to the melting temperature. This is very different from the behavior of the other rare gas crystals which grow completely rounded above 0.8 T{sub TP}. Helium bubbles formed as a product of the beta decay were observed using optical microscopy and the diffusion of smaller bubbles measured with dynamic light scattering. Bubble diffusion coefficients as high as 2.0 x 10{sup -16} m{sup 2}/s were measured for 10-50 nm bubbles. The bubbles move in response to a thermal gradient, with speeds between 1 {micro}m/hour and 100 {micro}m/hour for thermal gradients and temperatures appropriate to NIF targets.

  11. Effects of hydrogen flow on properties of hydrogen doped ZnO thin films prepared by RF magnetron sputtering

    Science.gov (United States)

    Hu, Yuehui; Chen, Yichuan; Chen, Jun; Chen, Xinhua; Ma, Defu

    2014-03-01

    The hydrogen doped ZnO (ZnO:H) thin films were deposited on quartz glass substrates by radio frequency magnetron sputtering. The doping characteristics of ZnO:H thin films with varied hydrogen flow ratio were investigated. At low hydrogen flow ratio (H2/(H2+Ar)≤0.02), the ZnO:H thin films exhibited dominant (002) peaks from X-ray diffraction and the lattice constants became smaller. The particles were mainly a columnar structure. The particles' size became smaller, and the island-like structure appeared on the thin films surface. In addition, the low resistivity properties of ZnO:H thin films was ascribed to the increase of the carriers concentration and carriers mobility; When the hydrogen flow ratio was more than 0.02 ( M≥0.02), two absorption bands at 1400-1800 cm-1 and 3200-3900 cm-1 were observed from the FT-IR spectra, which indicated that the ZnO:H thin films had typical Zn-H bonding, O-H bonding (hydroxyl), and Zn-H-O bonding (like-hydroxyl). The scanning electron microscope (SEM) results show that a large number of hydroxyl agglomeration formed an island-like structure on the thin films surface. The absorption peak at about 575 cm-1 in the Raman spectra indicated that oxygen vacancies (VO) defects were produced in the process of high hydrogen doping. In this condition, the low resistivity properties of ZnO:H thin films were mainly due to the increasing electron concentration resulted from VO. Meanwhile, the Raman absorption peaks at approximately 98 cm-1 and 436 cm-1 became weaker, and the (002) XRD diffraction peak quenched and the lattice constants increased, which shows that the ZnO:H thin films no longer presented a typical ZnO hexagonal wurtzite structure. With the increasing of hydrogen flow ratio, the optical transmittance of ZnO:H thin films in the ultraviolet band show a clear Burstein-Moss shift effect, which further explained that electron concentration was increased due to the increasing VO with high hydrogen doping concentration. Moreover

  12. Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Pier, M.

    1943-02-19

    A transcript is presented of a speech on the history of the development of hydrogenation of coal and tar. Apparently the talk had been accompanied by the showing of photographic slides, but none of the pictures were included with the report. In giving the history, Dr. Pier mentioned the dependence of much of the development of hydrogenation upon previous development in the related areas of ammonia and methanol syntheses, but he also pointed out several ways in which equipment appropriate for hydrogenation differed considerably from that used for ammonia and methanol. Dr. Pier discussed the difficulties encountered with residue processing, design of the reaction ovens, manufacture of ovens and preheaters, heating of reaction mixtures, development of steels, and development of compressor pumps. He described in some detail his own involvement in the development of the process. In addition, he discussed the development of methods of testing gasolines and other fuels. Also he listed some important byproducts of hydrogenation, such as phenols and polycyclic aromatics, and he discussed the formation of iso-octane fuel from the butanes arising from hydrogenation. In connection with several kinds of equipment used in hydrogenation (whose pictures were being shown), Dr. Pier gave some of the design and operating data.

  13. Hydrogen retention studies on lithiated tungsten exposed to glow discharge plasmas under varying lithiation environments using Thermal Desorption Spectroscopy and mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Castro, A. de, E-mail: alfonso.decastro@ciemat.es [Fusion National Laboratory-CIEMAT, Av Complutense 40, 28040 Madrid (Spain); Valson, P. [Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald (Germany); Tabarés, F.L. [Fusion National Laboratory-CIEMAT, Av Complutense 40, 28040 Madrid (Spain)

    2017-04-15

    For the design of a Fusion Reactor based on a liquid lithium divertor target and a tungsten first wall at high temperature, the interaction of the wall material with plasmas of significant lithium content must be assessed, as issues like fuel retention, tungsten embrittlement and enhanced sputtering may represent a showstopper for the selection of the first wall material compatible with the presence of liquid metal divertor. In this work we address this topic for the first time at the laboratory level, hot W samples (100 °C) have been exposed to Glow Discharges of H{sub 2} or Li-seeded H{sub 2} followed by in situ thermal desorption studies (TDS) of the uptake of H{sub 2} on the samples. Pure and pre-lithiated tungsten was investigated in order to evaluate the differential effect of Li ion implantation on H retention. Global particle balance was also used for the determination of trapped H into the full W wall of the plasma chamber. A factor of 3-4 lower retention was deduced for samples and main W wall exposed to H/Li plasma than that measured on pre-lithiated W.

  14. Auxilliary Dry Binding Properties of Some Hydrogenated Vegetable ...

    African Journals Online (AJOL)

    The ability of some hydrogenated vegetable oils to act as dry binder in direct compression tablet formulations was investigated using an instrumented rotary tablet press. The effect of these widely used tablet lubricants was compared to Avicel® PH 102, a standard, dry binding excipient in direct compression tablet ...

  15. Comparison of hydrogen storage properties of pure Mg and milled ...

    Indian Academy of Sciences (India)

    Division of Advanced Materials Engineering, Hydrogen & Fuel Cell Research Centre, Engineering Research Institute, Chonbuk National University, 567 Baekje-daero Deokjin-gu Jeonju 561-756, South Korea; Department of Materials Engineering, Graduate School, Chonbuk National University, 567 Baekje-daero ...

  16. Comparison of hydrogen storage properties of pure Mg and milled ...

    Indian Academy of Sciences (India)

    Administrator

    aDivision of Advanced Materials Engineering, Hydrogen & Fuel Cell Research Centre, Engineering Research. Institute, Chonbuk National University, 567 Baekje-daero Deokjin-gu Jeonju 561-756, South Korea. bDepartment of Materials Engineering, Graduate School, Chonbuk National University, 567 Baekje-daero.

  17. Sodium alanate nanoparticles - linking size to hydrogen storage properties

    NARCIS (Netherlands)

    Baldé, C.P.|info:eu-repo/dai/nl/304833983; Hereijgers, B.P.C.|info:eu-repo/dai/nl/314131116; Bitter, J.H.|info:eu-repo/dai/nl/160581435; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2008-01-01

    Important limitations in the application of light metal hydrides for hydrogen storage are slow kinetics and poor reversibility. To alleviate these problems doping and ball-milling are commonly applied, for NaAlH4 leading to particle sizes down to 150 nm. By wet-chemical synthesis we have prepared

  18. Hydrogen adsorption on bimetallic PdAu(111) surface alloys

    DEFF Research Database (Denmark)

    Takehiro, Naoki; Liu, Ping; Bergbreiter, Andreas

    2014-01-01

    The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining the stru...... into the physical effects underlying the observed adsorption behavior. Consequences of these findings for the understanding of hydrogen adsorption on bimetallic surfaces in general are discussed.......The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining...... and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight...

  19. Hydrogen storage development

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E. [Sandia National Labs., Livermore, CA (United States)

    1998-08-01

    A summary of the hydride development efforts for the current program year (FY98) are presented here. The Mg-Al-Zn alloy system was studied at low Zn levels (2--4 wt%) and midrange Al contents (40--60 wt%). Higher plateau pressures were found with Al and Zn alloying in Mg and, furthermore, it was found that the hydrogen desorption kinetics were significantly improved with small additions of Zn. Results are also shown here for a detailed study of the low temperature properties of Mg{sub 2}NiH{sub 4}, and a comparison made between conventional melt cast alloy and the vapor process material.

  20. THE INFLUENCE OF HYDROGEN ON THE PLASTIC PROPERTIES OF THE REINFORCING BARS

    Directory of Open Access Journals (Sweden)

    E. P. Baradyntseva

    2013-01-01

    Full Text Available The research carried out in laboratory of metal science on detection of hydrogen presence in reinforcement depending on period of aging and reinforcement profile and also its influence on plastic properties of reinforcing bar is described in this article. The method of glycerine tests was applied for identification of hydrogen presence in finished reinforcing bar, the essence of which is in the fact that at gas emission from metal the bubbles stay too long on the surface of cross samples under glycerin layer. The revealed regularities enable to recommend actions for providing stable mechanical properties of the heat-strengthened reinforcement by creation of conditions for lowering of steel saturation with hydrogen, preventing thereby occurrence of hydrogen embrittlement of reinforcement on JSC «BMZ» – management company of holding «BMK».

  1. Microstructure and mechanical property performance of commercial grade API pipeline steels in high pressure gaseous hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Douglas G. [DGS Metallurgical Solutions, Inc., Vancouver, WA, (United States); Boggess, Todd [Secat Inc., Lexington, KY, (United States); San Marchi, Chris; Somerday, Brian [Sandia National Laboratory, Livermore, CA, (United States); Jansto, Steve [Reference Metals Company, Bridgeville, PA, (United States); Muralidharan, Govindarajan [Oak Ridge National Laboratory, Oak Ridge, TN, (United States)

    2010-07-01

    The transportation of hydrogen by pipeline steels raises questions of the degradation of the mechanical properties of the steel. This study investigated the microstructure and mechanical property performance of pipeline steels in high pressure gaseous hydrogen. The performance of four commercially available pipeline steels have been tested in the presence of pressurized hydrogen gas at different pressures in the range of 5.5 MPa and 20.7 MPa. Microstructural characterizations, tensile testing, fracture testing and fatigue testing have been performed for each alloy. The results showed that the four pipeline steels perform differently in gaseous hydrogen. Yield strength does not seem to have a relevant effect on performance, which highlights the importance of the microstructure in determining the resistance of pipeline steels. Of the four microstructures, the polygonal ferrite/10% coarse acicular ferrite microstructure gave the best performance.

  2. Electrical properties and flux performance of composite ceramic hydrogen separation membranes

    DEFF Research Database (Denmark)

    Fish, J.S.; Ricote, Sandrine; O'Hayre, R.

    2015-01-01

    The electrical properties and hydrogen permeation flux behavior of the all-ceramic protonic/electronic conductor composite BaCe0.2Zr0.7Y0.1O3-δ/Sr0.95Ti0.9Nb0.1O3-δ (BCZY27/STN95: BS27) are evaluated. Conductivity and hydrogen permeability are examined as a function of phase volume ratios. Total...

  3. Two tools for applying chromatographic retention data to the mass-based identification of peptides during hydrogen/deuterium exchange experiments by nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Gershon, P D

    2010-12-15

    Two tools are described for integrating LC elution position with mass-based data in hydrogen-deuterium exchange (HDX) experiments by nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (nanoLC/MALDI-MS, a novel approach to HDX-MS). The first of these, 'TOF2H-Z Comparator', highlights peptides in HDX experiments that are potentially misidentified on the basis of mass alone. The program first calculates normalized values for the organic solvent concentration responsible for the elution of ions in nanoLC/MALDI HDX experiments. It then allows the solvent gradients for the multiple experiments contributing to an MS/MS-confirmed peptic peptide library to be brought into mutual alignment by iteratively re-modeling variables among LC parameters such as gradient shape, solvent species, fraction duration and LC dead time. Finally, using the program, high-probability chromatographic outliers can be flagged within HDX experimental data. The role of the second tool, 'TOF2H-XIC Comparator', is to normalize the LC chromatograms corresponding to all deuteration timepoints of all HDX experiments of a project, to a common reference. Accurate normalization facilitates the verification of chromatographic consistency between all ions whose spectral segments contribute to particular deuterium uptake plots. Gradient normalization in this manner revealed chromatographic inconsistencies between ions whose masses were either indistinguishable or separated by precise isotopic increments. Copyright © 2010 John Wiley & Sons, Ltd.

  4. Hydrogenation tuned the created ferromagnetic properties of Ni-doped nano-ZnO

    Science.gov (United States)

    Dakhel, A. A.

    2017-03-01

    Zn1- x Ni x O solid solution nanopowders were synthesised by thermal co-decomposition of Zn and Ni organic complexes method. The samples were characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD), and optical diffuse reflection spectroscopy. The XRD confirmed the formation of single phase of ZnO structure. The host unit-cell volume ( V cell) slightly decreased with Ni doping referring to the total doping of Ni ions. The hydrogenation increased the V cell of Ni-doped ZnO. The redshift of the bandgap of Ni-doped ZnO under hydrogenation is attributed to the formation of lattice strain defects through the creation of structural O-vacancies, which plays principle role of enhancing the room-temperature ferromagnetic (FM) properties. Therefore, the major objective of the present study is to investigate the significant effect of hydrogenation on the magnetic properties of Ni-doped ZnO. The appealing combined effect of doping and hydrogenation was discussed based on the Bound Magnetic Polarons (BMP) theory, as the O-vacancies are believed to be responsible for the enhancement of RT-FM properties with the presence of H-H interstitials (Hydrogenation). Therefore, hydrogenated Ni-doped ZnO nanopowders, owning these amazingly tunable magnetic manners, can be considered as a potential candidate for many applications such as optoelectronics and dilute magnetic semiconductors.

  5. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    Science.gov (United States)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves

  6. Activated aluminum hydride hydrogen storage compositions and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    Sandrock, Gary (Ringwood, NJ); Reilly, James (Bellport, NY); Graetz, Jason (Mastic, NY); Wegrzyn, James E. (Brookhaven, NY)

    2010-11-23

    In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

  7. Reversible hydrogen storage in the Ni-rich pseudo-binary Mg{sub 6}Pd{sub 0.25}Ni{sub 0.75} intermetallic compound: Reaction pathway, thermodynamic and kinetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Ponthieu, M. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); ICMPE/CNRS-UPEC UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Fernandez, J.F., E-mail: josefrancisco.fernandez@uam.es [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Cuevas, F. [ICMPE/CNRS-UPEC UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Ares, J.R.; Leardini, F.; Bodega, J.; Sanchez, C. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} reversibly absorbs 5.6 wt.% H in a two plateau pressure PCI. Black-Right-Pointing-Pointer The ternary phase depletes in Mg and Ni at low hydrogen pressure to form Mg{sub 2}Ni. Black-Right-Pointing-Pointer Reaction pathway of hydrogenation has been determined. Black-Right-Pointing-Pointer Enthalpy of the high pressure plateau is less negative than the one of pure Mg. Black-Right-Pointing-Pointer Low activation energy for desorption has been found for highly hydrided material. - Abstract: To improve the hydrogen storage properties of Mg{sub 6}Pd and to reduce its cost, Pd has been partly substituted by Ni at the solubility limit of the Mg{sub 6}(Pd,Ni) {rho}-phase. The attained composition is Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} as determined by Energy Dispersive X-Ray (EDX) and X-Ray Diffraction (XRD). Hydrogenation of this compound has been investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDX), Pressure-Composition-Isotherms (PCI) and thermal desorption analysis. On absorption, it decomposes in two steps as evidenced by two distinct plateau pressures. At low pressure, a partial segregation of Mg and Ni out of the pseudo-binary Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} {rho}-phase occurs leading to the formation of MgH{sub 2}, Mg{sub 2}Ni and Mg{sub 6}Pd{sub 0.7}Ni{sub 0.3} phases. At high pressure, the Mg{sub 6}Pd{sub 0.7}Ni{sub 0.3} phase disproportionates into MgH{sub 2}, Mg{sub 2}NiH{sub 4}, MgPd and Mg{sub 5}Pd{sub 2} phases. The hydrogenation reaction is reversible providing a hydrogen capacity of 5.6 wt.% H. The reaction enthalpy of the high pressure plateau is less negative than for pure Mg. Furthermore, the activation energy for H-desorption exhibits a dramatic decrease for hydrogen contents above 4 wt.% H, i.e. after the alloy disproportionation.

  8. First principles study on stability and hydrogen adsorption properties of Mg/Ti interface.

    Science.gov (United States)

    Dai, J H; Xie, R W; Chen, Y Y; Song, Y

    2015-07-07

    The hydrogenation and stability properties of the Mg/Ti interface are studied by first-principles calculations. The strain of lattice and movement of ions were imposed to search for a stable Mg/Ti interface. The anti-symmetrical configuration was found to be the most stable. The easiest transition pathway from anti-symmetrical to symmetrical configuration may be through the diagonal direction with no energy barrier. The hydrogen adsorption at distinguished positions in the Mg/Ti interface is investigated. The negative hydrogen adsorption energy reaches -0.991 eV at the top site in the interface, which will highly favor the thermodynamic stability of the Mg/Ti interface. The electronic structure is studied and it was found that the Ti acts as a hydrogen atom 'capturer' and strong interactions between H and its surrounding Ti and Mg atoms are expected. Thus, inserting Ti layers could create an interfacial zone where the adsorptions of hydrogen atoms may get stabilized and therefore improve the hydrogen storage properties of Mg.

  9. New Studies of the Physical Properties of Metallic Amorphous Membranes for Hydrogen Purification

    Directory of Open Access Journals (Sweden)

    Oriele Palumbo

    2017-02-01

    Full Text Available Amorphous metallic membranes display promising properties for hydrogen purification up to an ultrapure grade (purity > 99.999%. The hydrogen permeability through amorphous membranes has been widely studied in the literature. In this work we focus on two additional properties, which should be considered before possible application of such materials: the propensity to crystallize at high temperatures should be avoided, as the crystallized membranes can become brittle; the hydrogen solubility should be high, as solubility and permeability are proportional. We investigate the crystallization process and the hydrogen solubility of some membranes based on Ni, Nb, and Zr metals, as a function of Zr content, and with the addition of Ta or B. The boron doping does not significantly affect the crystallization temperature and the thermal stability of the membrane. However, the hydrogen solubility for p ~7 bar is as high as H/M ~0.31 at T = 440 °C and H/M ~0.27 at T = 485 °C. Moreover, the membrane does not pulverize even after repeated thermal cycles and hydrogenation processes up to 485 °C and 7 bar, and it retains its initial shape.

  10. Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

    Directory of Open Access Journals (Sweden)

    Jianxin Zou

    2012-01-01

    Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

  11. Improving the hydrogen storage properties of metal-organic framework by functionalization.

    Science.gov (United States)

    Xia, Liangzhi; Liu, Qing; Wang, Fengling; Lu, Jinming

    2016-10-01

    Based on the structure of MOF-808, different substituents were introduced to replace hydrogen atom on the phenyl ring of MOF-808. The GCMC method was used to study the effect of functional groups on the hydrogen storage properties of MOF-808-X (X = -OH, -NO2, -CH3, -CN, -I). The H2 uptakes and isosteric heat of adsorption were simulated at 77 K. The results indicate that all these substituents have favorable impact on the hydrogen storage capacity, and -CN is found to be the most promising substituent to improve H2 uptake. These results may be helpful for the design of MOFs with higher hydrogen storage capacity. Graphical abstract Atomistic structures of MOFs. (a) The structures of MOF-808-X. (b) Model of organic linker. Atom color scheme: C, gray; H, white; O, red; X, palegreen (X = -OH, -NO2, -CH3, -CN, -I).

  12. Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

    2008-06-10

    A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

  13. Tuning structural and magnetic properties of Fe films on Si substrates by hydrogenation processing

    Energy Technology Data Exchange (ETDEWEB)

    Sandu, S.G. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Bucharest University, Faculty of Physics, 077125 Bucharest-Magurele (Romania); Palade, P.; Schinteie, G. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Birsan, A. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Bucharest University, Faculty of Physics, 077125 Bucharest-Magurele (Romania); Trupina, L. [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania); Kuncser, V., E-mail: kuncser@infim.ro [National Institute of Materials Physics, 077125 Bucharest-Magurele (Romania)

    2014-02-15

    Highlights: • Fe films have been grown on Si(0 0 1) substrates and subsequently hydrogenated. • As deposited films present soft magnetic character and a strong magnetic texture. • Structural and magnetic properties can be tuned via hydrogenation treatments. • Ferromagnetic/semiconductor interfaces might be manipulated via hydrogenation. -- Abstract: In order to study specific phenomena at ferromagnetic/semiconducting interfaces, of potentially high interest in spintronics and information technology, structural aspects and magnetic properties of Fe thin films grown on Si(0 0 1) substrates by RF sputtering have been investigated using {sup 57}Fe conversion electron Mössbauer spectroscopy (CEMS) and magneto-optic Keer effect (MOKE). Films of different thicknesses have been deposited either directly on crystalline Si substrates or on Cu buffer layers. An inherent Fe oxide layer is observed in all as prepared films, with a relative thickness decreasing drastically with the deposition time. The Cu buffer layer does not diminish either the interfacial diffusion or the oxidation process. An efficient method to prepare sharper oxygen- and silicon-free interfaces for an improved spin injection, via thermal treatment in hydrogen atmosphere, is proposed. Accordingly, the hydrogenation treatments are very efficient in the modification of the ferromagnetic film structure, phase composition, magnetic properties and interfacial mixing.

  14. Derived properties from the dipole and generalized oscillator strength distributions of an endohedral confined hydrogen atom

    Science.gov (United States)

    Martínez-Flores, C.; Cabrera-Trujillo, R.

    2018-03-01

    We report the electronic properties of a hydrogen atom confined by a fullerene molecule by obtaining the eigenvalues and eigenfunctions of the time-independent Schrödinger equation by means of a finite-differences approach. The hydrogen atom confinement by a C60 fullerene cavity is accounted for by two model potentials: a square-well and a Woods–Saxon. The Woods–Saxon potential is implemented to study the role of a smooth cavity on the hydrogen atom generalized oscillator strength distribution. Both models characterize the cavity by an inner radius R 0, thickness Δ, and well depth V 0. We use two different values for R 0 and Δ, found in the literature, that characterize H@C60 to analyze the role of the fullerene cage size and width. The electronic properties of the confined hydrogen atom are reported as a function of the well depth V 0, emulating different electronic configurations of the endohedral cavity. We report results for the hyper-fine splitting, nuclear magnetic screening, dipole oscillator strength, the static and dynamic polarizability, mean excitation energy, photo-ionization, and stopping cross section for the confined hydrogen atom. We find that there is a critical potential well depth value around V 0 = 0.7 a.u. for the first set of parameters and around V 0 = 0.9 a.u. for the second set of parameters, which produce a drastic change in the electronic properties of the endohedral hydrogen system. These values correspond to the first avoided crossing on the energy levels. Furthermore, a clear discrepancy is found between the square-well and Woods–Saxon model potential results on the hydrogen atom generalized oscillator strength due to the square-well discontinuity. These differences are reflected in the stopping cross section for protons colliding with H@C60.

  15. The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Nordell, Bradley J.; Karki, Sudarshan; Nguyen, Thuong D.; Rulis, Paul; Caruso, A. N.; Paquette, Michelle M., E-mail: paquettem@umkc.edu [Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States); Purohit, Sudhaunshu S. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States); Li, Han; King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States); Dutta, Dhanadeep; Gidley, David [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lanford, William A. [Department of Physics, University at Albany, Albany, New York 12222 (United States)

    2015-07-21

    Because of its high electrical resistivity, low dielectric constant (κ), high thermal neutron capture cross section, and robust chemical, thermal, and mechanical properties, amorphous hydrogenated boron carbide (a-B{sub x}C:H{sub y}) has garnered interest as a material for low-κ dielectric and solid-state neutron detection applications. Herein, we investigate the relationships between chemical structure (atomic concentration B, C, H, and O), physical/mechanical properties (density, porosity, hardness, and Young's modulus), electronic structure [band gap, Urbach energy (E{sub U}), and Tauc parameter (B{sup 1/2})], optical/dielectric properties (frequency-dependent dielectric constant), and electrical transport properties (resistivity and leakage current) through the analysis of a large series of a-B{sub x}C:H{sub y} thin films grown by plasma-enhanced chemical vapor deposition from ortho-carborane. The resulting films exhibit a wide range of properties including H concentration from 10% to 45%, density from 0.9 to 2.3 g/cm{sup 3}, Young's modulus from 10 to 340 GPa, band gap from 1.7 to 3.8 eV, Urbach energy from 0.1 to 0.7 eV, dielectric constant from 3.1 to 7.6, and electrical resistivity from 10{sup 10} to 10{sup 15} Ω cm. Hydrogen concentration is found to correlate directly with thin-film density, and both are used to map and explain the other material properties. Hardness and Young's modulus exhibit a direct power law relationship with density above ∼1.3 g/cm{sup 3} (or below ∼35% H), below which they plateau, providing evidence for a rigidity percolation threshold. An increase in band gap and decrease in dielectric constant with increasing H concentration are explained by a decrease in network connectivity as well as mass/electron density. An increase in disorder, as measured by the parameters E{sub U} and B{sup 1/2}, with increasing H concentration is explained by the release of strain in the network and associated decrease in

  16. Some Properties of LaNi5-xAlx Metal Alloys and the Diffusion Coefficient and Solubility of Hydrogen in Cyclohexane

    NARCIS (Netherlands)

    Snijder, Erwin D.; Versteeg, Geert F.; Swaaij, Wim P.M. van

    1994-01-01

    Pressure-composition isotherms for hydrogen absorption and desorption have been measured for several alloys of the LaNi5-xAlx family at 298, 308, 323, 333, and 348 K, and the ΔHº and ΔSº of the hydride formation reaction were obtained. The equilibrium pressure is strongly related to the aluminum

  17. Microscopic and thermodynamic properties of dense semiclassical partially ionized hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T S; Dzhumagulova, K N; Gabdullin, M T [IETP, Al-Farabi Kazakh National University, 96a, Tole Bi St, Almaty, 050012 (Kazakhstan)

    2006-04-28

    Microscopic and thermodynamic properties of dense semiclassical partially ionized hydrogen plasma were investigated on the basis of pseudopotential models. Radial distribution functions (RDF) of particles were obtained using a system of the Ornstein-Zernike integral equations. The corrections to internal energy and the equation of state were calculated using RDF.

  18. Hydrogen bonding properties and intermediate structure of N-(2-carboxyphenyl)salicylidenimine

    NARCIS (Netherlands)

    Ligtenbarg, Alette G.J.; Hage, Ronald; Meetsma, Auke; Feringa, Ben L.

    1999-01-01

    The hydrogen bonding properties, the nature of the tautomeric structure and dimerization of N-(2-carboxyphenyl)salicylidenimine 1 has been studied. The crystal and molecular structure of 1 has been determined by single-crystal X-ray diffraction analysis. This compound forms a dimer in the solid

  19. Combustion gas properties. Part 3: Hydrogen gas fuel and dry air

    Science.gov (United States)

    Wear, J. D.; Jones, R. E.; Mcbride, B. J.; Beyerle, R. A.

    1985-01-01

    A series of computations has been made to produce the equilibrium temperature and gas composition for hydrogen gas fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0. Only sample tables and figures are provided in this report.

  20. Effect of hydrogen on Fe and Pd alloying and physical properties

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Buršík, Jiří; Zemanová, Adéla; Čízek, J.; Hruška, P.; Životský, O.

    2017-01-01

    Roč. 42, č. 10 (2017), s. 6885-6901 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : positron-lifetime spectroscopy * neutron-diffraction * magnetic-properties * palladium- hydrogen * induced defects * iron Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.582, year: 2016

  1. Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2012-03-01

    Full Text Available -1 ACS Appl. Mater. Interfaces 2012, 4, 1656-1665 dx.doi.org/10.1021/am2018089 Photoluminescence and Hydrogen Gas-Sensing Properties of Titanium Dioxide Nanostructures Synthesized by Hydrothermal Treatments Lucky M. Sikhwivhilu, Siyasanga Mpelane...

  2. Deuterium desorption from tungsten using laser heating

    Directory of Open Access Journals (Sweden)

    J.H. Yu

    2017-08-01

    Full Text Available Retention and desorption of hydrogenic species need to be accurately modeled to predict the tritium inventory of next generation fusion devices, which is needed both for tritium fuel recovery and for tritium safety concerns. In this paper, experiments on thermal desorption of deuterium from intrinsic polycrystalline tungsten defects using laser heating are compared to TMAP-7 modeling. The samples during deuterium plasma exposure were at a temperature of 373K for this benchmark study with ion fluence of 0.7–1.0 ×1024Dm−2. Following plasma exposure, a fiber laser (λ= 1100nm heated the samples to peak surface temperatures ranging from ∼500 to 1400K with pulse widths from 10ms to 1s, and 1 to 10 pulses applied to each sample. The remaining deuterium retention was measured using temperature programmed desorption (TPD. Results show that > 95% of deuterium is desorbed when the peak surface temperature reached ∼950K for > 1s. TMAP-7 is used to predict deuterium desorption from tungsten for a range of surface temperatures and heating durations, and is compared to previous work on desorption from beryllium codeposits.

  3. Effect of pressure on the solution structure and hydrogen bond properties of aqueous N-methylacetamide

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Rahul [Department of Chemistry, Indian Institute of Technology, Guwahati, Guwahati 781 039, Assam (India); Paul, Sandip, E-mail: sandipp@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology, Guwahati, Guwahati 781 039, Assam (India)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer NMA molecules are associated mostly through their hydrophobic methyl groups. Black-Right-Pointing-Pointer High pressure reduces association propensity causing dispersion of these moieties. Black-Right-Pointing-Pointer Orientational polarization of vicinal water molecules near O and H atoms of NMA. Black-Right-Pointing-Pointer NMA prefers to be a H-bond acceptor rather than a donor in interaction with water. Black-Right-Pointing-Pointer Energy of these hydrogen bonds reduces slightly at high pressure. -- Abstract: Effects of high pressure on hydrophobic and hydrogen bonding interactions are investigated by employing molecular dynamics (MD) simulations of aqueous N-methylacetamide (NMA) solutions. Such systems are of interest mainly because high pressure causes protein denaturation and NMA is a computationally effective model to understand the atomic-level picture of pressure-induced structural transitions of protein. Simulations are performed for five different pressure values ranging from 1 atm to 8000 atm. We find that NMA molecules are associated mostly through their hydrophobic methyl groups and high pressure reduces this association propensity, causing dispersion of these moieties. At high pressure, structural void decreases and the packing efficiency of water molecules around NMA molecules increases. Hydrogen bond properties calculations show favorable NMA-NMA hydrogen bonds as compared to those of NMA-water hydrogen bonds and preference of NMA to be a hydrogen bond acceptor rather than a donor in interaction with water.

  4. Role of the Edge Properties in the Hydrogen Evolution Reaction on MoS2.

    Science.gov (United States)

    Lazar, Petr; Otyepka, Michal

    2017-04-06

    Molybdenum disulfide, in particular its edges, has attracted considerable attention as possible substitute for platinum catalysts in the hydrogen evolution reaction (HER). The complex nature of the reaction complicates its detailed experimental investigations, which are mostly indirect and sample dependent. Therefore, density functional theory calculations were employed to study how the properties of the MoS2 Mo-edge influence the thermodynamics of hydrogen adsorption onto the edge. The effect of the computational model (one-dimensional nanostripe), border symmetry imposed by its length, sulfur saturation of the edge, and dimensionality of the material are discussed. Hydrogen adsorption was found to depend critically on the coverage of extra sulfur at the Mo edge. The bare Mo-edge and fully sulfur-covered Mo-edge are catalytically inactive. The most favorable hydrogen binding towards HER was found for the Mo-edge covered by sulfur monomers. This edge provides hydrogen adsorption free energies positioned around -0.25 eV at up to 50 % hydrogen coverage, close to the experimental values of overpotential needed for the HER reaction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Effect of Gaseous Impurities on Long-Term Thermal Cycling and Aging Properties of Complex Hydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Dhanesh [Primary Contact; Lamb, Joshua; Chien, Wen-Ming; Talekar, Anjali; and Pal, Narendra

    2011-03-28

    This program was dedicated to understanding the effect of impurities on Long-Term Thermal Cycling and aging properties of Complex Hydrides for Hydrogen Storage. At the start of the program we found reversibility between Li2NH+LiH LiH+LiNH2 (yielding ~5.8 wt.%H capacity). Then we tested the effect of impurity in H2 gas by pressure cycling at 255°C; first with industrial gas containing ppm levels of O2 and H2O as major impurities. Both these impurities had a significant impact on the reversibility and decreased the capacity by 2.65 wt.%H. Further increase in number of cycles from 500 to 1100 showed only a 0.2 wt%H more weight loss, showing some capacity is still maintained after a significant number of cycles. The loss of capacity is attributed to the formation of ~55 wt% LiH and ~30% Li2O, as major contaminant phases, along with the hydride Li2NH phase; suggesting loss of nitrogen during cycling. The effect of 100 ppm H2O in H2 also showed a decrease of ~2.5 wt.%H (after 560 cycles), and 100ppm O2 in H2; a loss of ~4.1 wt.%. Methane impurity (100 ppm, 100cycles), showed a very small capacity loss of 0.9 wt.%H under similar conditions. However, when Li3N was pressure cycled with 100ppmN2-H2 there were beneficial effects were observed (255oC); the reversible capacity increased to 8.4wt.%H after 853 cycles. Furthermore, with 20 mol.%N2-H2 capacity increased to ~10 wt.%H after 516 cycles. We attribute this enhancement to the reaction of nitrogen with liquid lithium during cycling as the Gibbs free energy of formation of Li3N (Go = -98.7 kJ/mol) is more negative than that of LiH (Go = -50.3 kJ/mol). We propose that the mitigation of hydrogen capacity losses is due to the destabilization of the LiH phase that tends to accumulate during cycling. Also more Li2NH phase was found in the cycled product. Mixed Alanates (3LiNH2:Li3AlH6) showed that 7 wt% hydrogen desorbed under dynamic vacuum. Equilibrium experiments (maximum 12 bar H2) showed up to 4wt% hydrogen reversibly

  6. An infrared measurement of chemical desorption from interstellar ice analogues

    Science.gov (United States)

    Oba, Y.; Tomaru, T.; Lamberts, T.; Kouchi, A.; Watanabe, N.

    2018-03-01

    In molecular clouds at temperatures as low as 10 K, all species except hydrogen and helium should be locked in the heterogeneous ice on dust grain surfaces. Nevertheless, astronomical observations have detected over 150 different species in the gas phase in these clouds. The mechanism by which molecules are released from the dust surface below thermal desorption temperatures to be detectable in the gas phase is crucial for understanding the chemical evolution in such cold clouds. Chemical desorption, caused by the excess energy of an exothermic reaction, was first proposed as a key molecular release mechanism almost 50 years ago1. Chemical desorption can, in principle, take place at any temperature, even below the thermal desorption temperature. Therefore, astrochemical network models commonly include this process2,3. Although there have been a few previous experimental efforts4-6, no infrared measurement of the surface (which has a strong advantage to quantify chemical desorption) has been performed. Here, we report the first infrared in situ measurement of chemical desorption during the reactions H + H2S → HS + H2 (reaction 1) and HS + H → H2S (reaction 2), which are key to interstellar sulphur chemistry2,3. The present study clearly demonstrates that chemical desorption is a more efficient process for releasing H2S into the gas phase than was previously believed. The obtained effective cross-section for chemical desorption indicates that the chemical desorption rate exceeds the photodesorption rate in typical interstellar environments.

  7. Properties of hydrogen and hydrogen-vacancy complexes in the rutile phase of titanium dioxide

    Science.gov (United States)

    Filippone, F.; Mattioli, G.; Alippi, P.; Amore Bonapasta, A.

    2009-12-01

    The interaction of atomic H with host atoms and oxygen vacancies (VO) in the rutile phase of the TiO2 metal oxide has been investigated by using density-functional theory-local spin density (DFT-LSD) and DFT-LSD+U theoretical methods. The achieved results show that H in rutile presents quite different and peculiar properties with respect to other semiconductors and metal oxides. It behaves indeed neither as an amphoteric impurity, as it does in Si and GaAs, nor as a shallow donor, as it has been proposed in ZnO. Moreover, H in rutile represents a failure of a theoretical model proposing a universal alignment of the H-induced electronic level in the energy gaps of semiconductors, which predicts a shallow donor behavior of H in ZnO and TiO2 . Present results show indeed that H behaves as a deep donor in rutile and always forms an OH+ complex, independent of the position of the Fermi energy. This very unusual behavior of H can be accounted for by a peculiar property of TiO2 regarding its capability of localizing extra electrons at Ti+3 sites. The electron lost by H can be accommodated indeed by a Ti+4 atom which evolves in a Ti+3 defect. This accounts for the deep behavior of H and implies that the electronic level it induces in the TiO2 energy gap has, actually, a Ti+3 character quite similar to that characterizing an O vacancy (VO) , thus distinguishing H in rutile from H in other semiconductors. Finally, H can form stable H-VO complexes where it takes the place of the missing O atom by forming a bond with a prevailing ionic character, at variance with a multicenter bond model proposed for the same complexes in ZnO.

  8. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    Science.gov (United States)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to

  9. Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppett, W.K. [Argonne National Lab., IL (United States)

    1998-03-01

    A systematic study has been initiated to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with the hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, four heats of alloys (BL-63, BL-71, and T87, plus 44 from General Atomics) are being evaluated. Other variables of interest are the effect of initial grain size on hydrogen uptake and tensile properties, and the synergistic effects of oxygen and hydrogen on the tensile behavior of the alloys. Experiments conducted thus far on specimens of various V-Cr-Ti alloys exposed to pH{sub 2} levels of 0.01 and 3 {times} 10{sup {minus}6} torr showed negligible effect of H{sub 2} on either maximum engineering stress of uniform/total elongation. Further, preliminary tests on specimens annealed at different temperatures showed that grain size variation by a factor of {approx}2 had a negligible effect on tensile properties.

  10. Hydrogen Storage Performances of REMg11Ni (RE = Sm, Y) Alloys Prepared by Mechanical Milling

    Science.gov (United States)

    Zhang, Yanghuan; Cui, Songsong; Yuan, Zeming; Gao, Jinliang; Dong, Xiaoping; Qi, Yan; Guo, Shihai

    2017-11-01

    This study adopted mechanical milling to prepare Mg-based REMg11Ni (RE = Sm, Y) hydrogen storage alloys. The alloy structures were examined by X-ray diffraction and transmission electron microscopy. The isothermal hydrogenation thermodynamics and kinetics were determined by an automatic Sievert apparatus. The non-isothermal dehydrogenation performance of the alloys was tested by differential scanning calorimetry and thermogravimetry at different heating rates. The results showed a nanocrystalline and amorphous tendency for the alloys. The YMg11Ni alloy exhibited a larger hydrogen absorption capacity, faster hydriding rate, and lower temperature of onset hydrogen desorption than the SmMg11Ni alloy. The hydrogen desorption temperatures of the REMg11Ni (RE = Sm, Y) alloys were 557.6 K and 549.8 K (284.6 °C and 276.8 °C), respectively. The hydrogen desorption property of the RE = Y alloy was found superior to the RE = Sm alloy based on the time required to absorb 3 wt pct H2, i.e., the time needed by the RE = Y alloy was reduced to 1106, 456, 363, and 180 s, respectively, corresponding to the hydrogen desorption temperatures of 593 K, 613 K, 633 K, and 653 K (320 °C, 340 °C, 360 °C, and 380 °C), compared to 1488, 574, 390, and 192 s for the RE = Sm alloy under identical conditions. The dehydrogenation activation energies were 100.31 and 98.01 kJ/mol for the REMg11Ni (RE = Sm, Y) alloys, respectively, which agreed with those of the RE = Y alloy showing a superior hydrogen desorption property.

  11. The influence of the small platinum clusters on hydrogen sorption properties

    Science.gov (United States)

    Martyła, Agnieszka; Przekop, R. E.; Osińska-Broniarz, Monika; Kopczyk, M.; Rybka, J. D.; Kirszensztejn, P.

    2017-11-01

    Hydrogen sorption abilities of Pt-B2O3/Al2O3 systems with different molar ratio of oxides obtained by sol-gel method were examined. Platinum was introduced by surface impregnation. Main goal of the research was to check an influence of metallic component (platinum) on sorption properties of B2O3/Al2O3 binary oxides. The oxide systems were characterized using XRD and TEM. Hydrogen adsorption was tested in the volumetric system and TPD measurements were taken. Results show that the amount of adsorbed hydrogen depends not only on the amount of platinum in the system but also on the type of oxide support and mainly on the content of boria.

  12. LiBH4/SBA-15 Nanocomposites Prepared by Melt Infiltration under Hydrogen Pressure: Synthesis and Hydrogen Sorption Properties

    NARCIS (Netherlands)

    Ngene, P.; Adelhelm, P.A.; Beale, A.M.; de Jong, K.P.; de Jongh, P.E.

    2013-01-01

    Lithium borohydride (LiBH4) is a promising material for hydrogen storage, with a gravimetric hydrogen content of 18.5%. However, the thermodynamics and kinetics of its hydrogen release and uptake need to be improved before it can meet the requirements for mobile applications. In this study, we

  13. Synthesis and enhanced microwave absorption properties: a strongly hydrogenated TiO2 nanomaterial

    Science.gov (United States)

    Xu, Jianle; Qi, Xiaosi; Luo, Chengzhi; Qiao, Jie; Xie, Ren; Sun, Yuan; Zhong, Wei; Fu, Qiang; Pan, Chunxu

    2017-10-01

    Due to its improved physical and chemical performances, a strongly hydrogenated TiO2 was designed and produced successfully by using a sealing-transfer reduction method at a relatively low temperature (425 °C). The microstructures, electromagnetic and microwave absorbing properties were investigated in detail. Experimental results revealed that: (1) the minimum reflection loss (RL) value of the hydrogenated TiO2 up to -53.8 dB (99.999 99% of EM wave attenuation) was reached at 11.2 GHz, and the RL values below -20 dB (99%) were obtained in a frequency range of 7.3-16.8 GHz. (2) Compared to pristine TiO2 and black TiO2 in other reports, the present hydrogenated TiO2 exhibited greatly improved microwave absorption performance. Moreover, the mechanism was also discussed. It was demonstrated that the excellent microwave absorption performance of the black TiO2 arose from the strong dielectric loss, excellent impedance matching and attention loss due to associated relaxation and interfacial polarization. It is expected that the hydrogenated TiO2 exhibits great potential applications in the area of high performance microwave absorbing materials. In addition, it is believed that the black TiO2 @ magnetic metals composites will display an excellent microwave absorbing property.

  14. Adsorption properties of polyvinyl-alcohol-grafted particles toward genistein driven by hydrogen-bond interaction.

    Science.gov (United States)

    Zhang, Yanyan; Gao, Baojiao; Xu, Zeqing

    2013-05-09

    The adsorption properties of polyvinyl alcohol (PVA)-grafted silica gel particles PVA/SiO2 toward genistein are researched in this paper. The effects of the main factors on the adsorption properties are investigated, the adsorption mechanism is explored in depth, and the adsorption thermodynamics is researched. The experimental results show that the conventional hydrogen bond is formed between the hydroxyl groups with high density on the surfaces of PVA/SiO2 and the phenolic hydroxyl groups in genistein, while π-type hydrogen bond is formed between the hydroxyl groups of PVA/SiO2 and the conjugated aromatic rings. It is the two types of hydrogen bond that make the functional composite particles PVA/SiO2 produce very strong physical adsorption toward genistein. The competitive adsorption of the solvent can have severe negative impact on the adsorption capacity of genistein. Increasing temperature will weaken the hydrogen-bond interaction between PVA/SiO2 particles and genistein. The existence of electrolytes in the protic solvent will affect the adsorption negatively. The adsorption process of PVA/SiO2 particles toward genistein is exothermic and driven by enthalpy. The adsorption isotherm data matches the Langmuir model.

  15. Catalytic effect of monoclinic WO{sub 3}, hexagonal WO{sub 3} and H{sub 0.23}WO{sub 3} on the hydrogen sorption properties of Mg

    Energy Technology Data Exchange (ETDEWEB)

    Tonus, Florent; Bobet, Jean-Louis [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, Pessac F-33608 (France); Fuster, Valeria; Urretavizcaya, Guillermina; Castro, Facundo J. [Centro Atomico Bariloche (CNEA, CONICET), Instituto Balseiro (UNCUYO), Av. Bustillo 9500, San Carlos de Bariloche (Argentina)

    2009-05-15

    The H sorption properties of mixtures Mg + WO{sub 3} (having various structures) and Mg + H{sub 0.23}WO{sub 3} are reported. First, the higher conversion of Mg into MgH{sub 2} during reactive mechanical grinding (under 1.1 MPa of H{sub 2}) for higher WO{sub 3} content is due to the improvement of the milling efficiency. Then, it is shown that the hydrogen absorption properties are almost independent of the crystal structure of the catalyst and that only the particles' size and the specific surface play a major role. Finally, for the desorption process, it appears that the chemical composition and structure of the catalyst, together with the particle size and specific surface have an effect. (author)

  16. Properties of hydrogenated amorphous germanium nitrogen alloys prepared by reactive sputtering

    Science.gov (United States)

    Honma, I.; Kawai, H.; Komiyama, H.; Tanaka, K.

    1989-02-01

    Hydrogenated amorphous germanium-nitrogen alloys (a-GeNx:H) were synthesized as a new group of amorphous semiconductors by rf(13.56 MHz) reactive sputtering of a Ge target in a gas mixture of Ar+N2+H2 under a variety of deposition conditions such as gas ratio, rf-discharge power, and substrate temperature. Structural, optical, and electrical properties of those a-GeNx:H alloys were systematically measured and are discussed in relation to their preparation conditions. The optical band gap E04 of a-GeNx:H alloys could be continuously controlled in the range from 1.1 eV to 3.3 eV primarily depending on the atomic N/Ge ratio in the film. The role of hydrogen and nitrogen in the optical and electrical properties of the material is also crucially demonstrated.

  17. Study on the Hydrogen Generation Rules of Coal Oxidation at Low Temperature

    OpenAIRE

    Shao He; Zhou Fubao; Chen Kaiyan; Cheng Jianwei; Melogh, Palu H.

    2014-01-01

    Based on a hydrogen desorption experiment and a comparative experiment of low-temperature coal oxidation performed prior to and after hydrogen desorption, this paper demonstrates the occurrence of hydrogen adsorption in coal at room temperature and reveals that the hydrogen generated in the process of coal oxidation originates from coal oxidation and desorption. The results show that the hydrogen accumulation generated only by coal oxidation and the hydrogen accumulation generated...

  18. Structural properties of hydrogen isotopes in solid phase in the context of inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    Guerrero Carlo

    2013-11-01

    Full Text Available Quality of Deuterium-Tritium capsules is a critical aspect in Inertial Confinement Fusion. In this work, we present a Quantum Molecular Dynamics methodology able to model hydrogen isotopes and their structural molecular organisation at extreme pressures and cryogenic temperatures (< 15 K. Our study sets up the basis for a future analysis on the mechanical and structural properties of DT-ice in inertial confinement fusion (ICF target manufacturing conditions.

  19. Biogenic Properties of Deep Waters from the Black Sea Reduction (Hydrogen Sulphide) Zone for Marine Algae

    OpenAIRE

    Polikarpov, Gennady G.; Lazorenko, Galina Е.; Тereschenko, Natalya N.

    2015-01-01

    Abstract Generalized data of biogenic properties investigations of the Black Sea deep waters from its reduction zone for marine algae are presented. It is shown on board and in laboratory that after pre-oxidation of hydrogen sulphide by intensive aeration of the deep waters lifted to the surface of the sea, they are ready to be used for cultivation of the Black Sea unicellular, planktonic, and multicellular, benthic, algae instead of artificial medium. Naturally balanced micro- and macroeleme...

  20. Effect of hydrogen charging on the mechanical properties of medium strength aluminium alloys 2091 and 2014

    DEFF Research Database (Denmark)

    Bandopadhyay, A.; Ambat, Rajan; Dwarakadasa, E.S.

    1992-01-01

    Cathodic hydrogen charging in 3.5% NaCl solution altered the mechanical properties of 2091-T351 (Al-Cu-Li-Mg-Zr) determined by a slow (10(-3)/s) strain rate tensile testing technique. UTS and YS decreased in the caw of 2091-T351 and 2014-T6(Al-Cu-Mn-Si-Mg) with increase in charging current density...

  1. Comparison of rheological properties of graphene / carbon nanotube hydrogenated oil based biodegradable drilling fluid

    Science.gov (United States)

    Chai, Y. H.; Yusup, S.; Chok, V. S.; Irawan, S.; Singh, J. D. B. S.; Chin, B. L. F.

    2017-06-01

    An experimental investigation has been carried out to investigate the rheological properties of graphene / carbon nanotube hydrogenated oil based biodegradable drilling fluid at different nanoparticle loadings. The rheological behaviours of interest in this investigation are the viscosity and shear stresses of two different nanofluids respectively. The limiting parameters in this study are 25 ppm, 50 ppm and 100 ppm weight concentration at operating temperature ranging from 30°C to 50°C. Both nanofluids are subjected to shear rate ranging from 0 - 140 s-1 for comparison of rheological behaviours. Both samples’ viscosity reduces to base fluid’s viscosity value at higher shear rate with carbon nanotube-hydrogenated oil yielding higher viscosity compared to graphene-hydrogenated oil for all nanoparticle loadings at lower shear rate. Shear stress analysis also shows similar results with carbon nanotube based samples showing higher stress between the two at all particle loadings. Both samples show Newtonian behaviour that is similar to base fluid even at higher particle loadings. Analysis revealed both nanofluids yields close to zero yield stress even with the presence of graphene or carbon nanotube particles. The significance of this study shows that addition of low nanomaterials for enhancement of drilling fluids can improve its thermophysical properties without compromising the quality of drilling fluids such as viscosity and shear stress properties.

  2. First principle investigations of the physical properties of hydrogen-rich MgH2

    KAUST Repository

    Zarshenas, Mohammed

    2013-11-28

    Hydrogen being a cleaner energy carrier has increased the importance of hydrogen-containing light metal hydrides, in particular those with large gravimetric hydrogen density like magnesium hydride (MgH2). In this study, density functional and density functional perturbation theories are combined to investigate the structural, elastic, thermodynamic, electronic and optical properties of MgH2. Our structural parameters calculated with those proposed by Perdew, Burke and Ernzerof generalized gradient approximation (PBE-GGA) and Wu-Cohen GGA (WC-GGA) are in agreement with experimental measurements, however the underestimated band gap values calculated using PBE-GGA and WC-GGA were greatly improved with the GGA suggested by Engle and Vosko and the modified Becke-Johnson exchange correlation potential by Trans and Blaha. As for the thermodynamic properties the specific heat values at low temperatures were found to obey the T3 rule and at higher temperatures Dulong and Petit\\'s law. Our analysis of the optical properties of MgH2 also points to its potential application in optoelectronics. © 2013 The Royal Swedish Academy of Sciences.

  3. Electro-Optical Properties of Hydrogenated Si-Doped CdO

    Science.gov (United States)

    Dakhel, A. A.

    2017-10-01

    The optoelectronic properties of CdO films could be controlled and improved for transparent conducting (TC) purposes by means of doping. In the present work, several sets of CdO thin films hydrogenated and doped with different amounts of silicon were prepared on glass substrates by a thermal deposition technique in order to improve their TC properties. The x-ray diffraction method was used to study the crystal structural variations in CdO films as a consequence of Si(H) doping. Optical properties were studied by means of optical absorption and reflection spectroscopy. The observed blue-shifting in the optical bandgap by Si(H) doping was attributed to the Moss-Burstein effect with reduced structural bandgap by point defects created during the process of doping. The mechanism of the hydrogenation process was explained by the dissociation of hydrogen molecules into atoms/ions, which in turn interacted with structural oxygen ions leading to the creation of oxygen vacancies. The creation of oxygen vacancies caused increases in electron concentration (N el) and electrical conductivity (σ). The results showed that Si(H) doping of host CdO films significantly increased their conductivity, mobility, and carrier concentration by ˜ 69, 5.6, and 12.3 times, respectively. The results confirm that Si(H) doping is effective for using CdO films in transparent conducting oxide applications.

  4. Thermodynamics and Kinetics of Phase Transformations in Hydrogen Storage Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ceder, Gerbrand; Marzari, Nicola

    2011-08-31

    The aim of this project is to develop and apply computational materials science tools to determine and predict critical properties of hydrogen storage materials. By better understanding the absorption/desorption mechanisms and characterizing their physical properties it is possible to explore and evaluate new directions for hydrogen storage materials. Particular emphasis is on the determination of the structure and thermodynamics of hydrogen storage materials, the investigation of microscopic mechanisms of hydrogen uptake and release in various materials and the role of catalysts in this process. As a team we have decided to focus on a single material, NaAlH{sub 4}, in order to fully be able to study the many aspects of hydrogen storage. We have focused on phase stability, mass transport and size-dependent reaction mechanisms in this material.

  5. Hydrogen storage properties in the Mg{sub 0.75}Ta{sub 0.25} system prepared by mechanical milling; Propiedades de almacenamiento de hidrogeno en el sistema Mg{sub 0.75}Ta{sub 0.25} preparado por molienda mecanica

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. A.

    2016-07-01

    Magnesium and most of its mixtures have slow sorption-desorption kinetics of hydrogen, which limits their technological application and their viability from the economic view point. Recently, has been observed that by the synthesis of advanced materials, using the mechanical milling technique, positive changes in the kinetics are introduced. In order to improve the sorption-desorption hydrogen properties, in the present work a mixture consisting of Mg{sub 0.75}Ta{sub 0.25} was prepared using methanol as process control agent. To this end, the first methodological step was to carry out, by means of the mechanical milling technique, the synthesis of the mixture Mg{sub 0.75}Ta{sub 0.25} in a Spex type vibratory mill at times of 6, 12, 18 and 24 h. Subsequently, the material was characterized by different analytical techniques such as scanning electron microscopy with elemental analysis, X-ray diffraction and N{sub 2} physisorption analysis. Subsequently, hydrogen sorption experiments were carried out in a Parr reactor to evaluate the hydrogen storage capacity of the mixture, varying temperature parameters, pressure and time, in order to determine the optimal parameters of hydrogen sorption. The characterization of the hydrogen storage capacity was analyzed by the thermogravimetric analysis/differential scanning calorimetry technique coupled to a mass spectrometer. X ray diffraction analysis reveals that there is a mixture between the starting compounds, with an important refinement of the microstructure as a consequence of the mechanical milling process. The results of the hydrogen sorption tests at 1, 5 and 10 cycles showed that the storage of hydrogen in the Mg{sub 0.75}Ta{sub 0.25} mixture can be carried out at a temperature of 25 degrees Celsius with a pressure of 2 atm and a contact time of 1 h. (Author)

  6. The effect of electron induced hydrogenation of graphene on its electrical transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sung Oh [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Teizer, Winfried [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); WPI-Advanced Institute for Materials Research, Tohoku University, Sendai (Japan)

    2013-07-22

    We report a deterioration of the electrical transport properties of a graphene field effect transistor due to energetic electron irradiation on a stack of Poly Methyl Methacrylate (PMMA) on graphene (PMMA/graphene bilayer). Prior to electron irradiation, we observed that the PMMA layer on graphene does not deteriorate the carrier transport of graphene but improves its electrical properties instead. As a result of the electron irradiation on the PMMA/graphene bilayer, the Raman “D” band appears after removal of PMMA. We argue that the degradation of the transport behavior originates from the binding of hydrogen generated during the PMMA backbone secession process.

  7. Physical Properties and Hydrogen-Bonding Network of Water-Ethanol Mixtures from Molecular Dynamics Simulations.

    Science.gov (United States)

    Ghoufi, A; Artzner, F; Malfreyt, P

    2016-02-04

    While many numerical and experimental works were focused on water-ethanol mixtures at low ethanol concentration, this work reports predictions of a few physical properties (thermodynamical, interfacial, dynamical, and dielectrical properties) of water-ethanol mixture at high alcohol concentrations by means of molecular dynamics simulations. By using a standard force field a good agreement was found between experiment and molecular simulation. This was allowed us to explore the dynamics, structure, and interplay between both hydrogen-bonding networks of water and ethanol.

  8. Polymer pipes for distributing mixtures of hydrogen and natural gas. Evolution of their transport and mechanical properties after an ageing under an hydrogen environment

    Energy Technology Data Exchange (ETDEWEB)

    Klopffer, Marie-Helene [IFP (France); Berne, Philippe [CEA (France); Castagnet, Sylvie [ENSMA (France); Weber, Mathilde [Air Liquide (Canada); Hochstetter, Gilles [Arkema (France); Espuche, Eliane [INSA Lyon (France)

    2010-07-01

    With the development of hydrogen as an energy vector, its delivery and transport from the production site to the end user remains an issue. Indeed, the key challenge to overcome is the high hydrogen permeation through existing polymer infrastructures used for natural gas distribution (Polyethylene pipes, components as connecting parts). This high flow rate of hydrogen through polymer has to be taken into account for safety and economical requirements. This 3-year project investigates pure hydrogen gas and mixtures (20% CH4 - 80% H2) in pipelines made of engineering polymers to develop and assess material solutions to cope with today problems for H2 distribution. Materials such as polyethylene (PE100) and polyamide 11 (PA11) have been studied. PE100 is considered as a reference material as it is used today in natural gas distribution pipes. PA11 should allow a higher operating pressure combined with better gas-barrier performances. Test benches and protocols for testing materials in terms of mechanical and barrier properties were first developed. The materials have then been studied in terms of barrier, mechanical properties and on a microstructural point of view. The properties of the raw material and samples after ageing in presence of hydrogen in various conditions were compared to assess the long term behaviour in service. These results as well as the comparison between PA11 and PE are presented. (orig.)

  9. DEUTERIUM, TRITIUM, AND HELIUM DESORPTION FROM AGED TITANIUM TRITIDES. PART I.

    Energy Technology Data Exchange (ETDEWEB)

    Shanahan, K; Jeffrey Holder, J

    2006-07-10

    Six new samples of tritium-aged bulk titanium have been examined by thermal desorption and isotope exchange chemistry. The discovery of a lower temperature hydrogen desorption state in these materials, previously reported, has been confirmed in one of the new samples. The helium release of the samples shows the more severe effects obtained from longer aging periods, i.e. higher initial He/M ratios. Several of the more aged samples were spontaneously releasing helium. Part I will discuss the new results on the new lower temperature hydrogen desorption state found in one more extensively studied sample. Part II will discuss the hydrogen/helium release behavior of the remaining samples.

  10. Effect of bleaching teeth with hydrogen peroxide on the morphology, hydrophilicity, and mechanical and tribological properties of the enamel

    OpenAIRE

    Rodrigues, F. T.; Serro, A. P.; Polido, M.; Ramalho, A.; Figueiredo-Pina, C. G.

    2017-01-01

    The tooth whitening process is intended to restore the original color of teeth. It consists of the application of oxidizing agents, including hydrogen peroxide. Although these products considerably improve the color of teeth, their effects on other properties of enamel are not fully understood. This work aimed to study the effects of hydrogen peroxide concentration on hydrophilicity, roughness, morphology, and mechanical and tribological properties of human tooth enamel. Human teeth were subj...

  11. Effect of hydrogen on properties of diode structures with Pd/GaAs/InGaAs quantum wells

    CERN Document Server

    Karpovich, I A; Shobolov, E L; Zvonkov, B N

    2002-01-01

    The effect of hydrogen on the photoelectric properties and on the photoluminescence of the Pd/GaAs/InGaAs quantum well diode structures was investigated. The effect of the GaAs anodic oxide thickness on the structure parameters was found and its optimal thickness for the hydrogen sensors was determined. The essential importance of the metal bridges in the thin oxide layers for the current voltage characteristic was established. It was shown that quantum wells increase the sensitivity of the structures to hydrogen. The defect formation during the deposition of the Pd electrode on the natural and anodized GaAs surface was investigated using the quantum wells as the local defect probes. The possibility of the hydrogen passivation of the defects in the diode structures by introduction of the atomic hydrogen through the Pd electrode in a molecular hydrogen atmosphere was proved

  12. Hydrogen storage in multi-walled carbon nanotubes decorated with palladium nanoparticles using laser ablation/chemical reduction methods

    Science.gov (United States)

    Mehrabi, M.; Parvin, P.; Reyhani, A.; Mortazavi, S. Z.

    2017-09-01

    Hydrogen storage properties of multi-walled carbon nanotubes (MWCNTs) decorated by palladium nanoparticles (Pd NPs) are investigated using laser ablation and chemical reduction methods, revealing great differences between the two techniques. In the case of laser ablation, the hydrogen uptake is elevated with the Pd content up to a certain value and then undergoes a notable drop, whereas the hydrogen content linearly scales up with the Pd loading during the chemical reduction method. When the Pd loading is low, the storage capacity of the laser treated samples is higher than those decorated via the other technique of interest. During laser ablation, the larger Pd content is accompanied by plentiful pore formation, leading to larger pore sizes at higher doses, which seriously reduces the hydrogen uptake. Moreover, the desorption temperature of hydrogen notably increases in terms of Pd loading. In comparison, the laser ablation method undergoes a relatively smaller desorption temperature, mainly due to the larger pore size/volume.

  13. In-situ plasma hydrogenated TiO{sub 2} thin films for enhanced photoelectrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Aadesh P.; Kodan, Nisha [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Mehta, Bodh R., E-mail: brmehta@physics.iitd.ac.in [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Dey, Avishek; Krishnamurthy, Satheesh [Materials Engineering, The Open University, Milton Keynes, MK7 6AA (United Kingdom)

    2016-04-15

    Highlights: • Growth of TiO{sub 2} thin films with in-situ plasma hydrogenation. • Presence of Ti{sup 2+} states in addition to Ti{sup 3+} states present in pristine TiO{sub 2}. • Change in VBM, work function and band gap in iH:TiO{sub 2}. • Enhanced photocurrent density as compared to pristine TiO{sub 2} films. - Abstract: In this paper, we report the effect of in-situ plasma hydrogenation of TiO{sub 2} (iH:TiO{sub 2}) thin films by the incorporation of known amount of hydrogen in the Ar plasma during rf-sputter deposition of TiO{sub 2} films. As compared to pristine TiO{sub 2} films (∼0.43 mA/cm2 at 0.23 V vs Ag/AgCl), hydrogenated TiO{sub 2} showed enhanced photoelectrochemical activity in terms of improved photocurrent density of ∼1.08 mA/cm2 (at 0.23 V vs Ag/AgCl). These results are explained in terms of reduction in band gap energy, shift in valence band maximum away from the Fermi level, improved donor density and more negative flat band potential in iH:TiO{sub 2} sample. The presence of Ti{sup 2+} states in iH:TiO{sub 2} films in addition to Ti{sup 3+} states in pristine TiO{sub 2} act as additional electronic states in the TiO{sub 2} band gap and increases the optical absorption in the visible region. This method of in-situ hydrogenation can be used as a general method for improving the properties of metal oxide thin films for photoelectrochemical and photocatalytic applications.

  14. Transport Properties of Spin-Polarized Atomic Hydrogen Using Generalized Scattering Theory

    Science.gov (United States)

    Joudeh, B. R.; Sandouqa, A. S.

    2018-02-01

    Our results for the scattering and thermophysical properties of spin-polarized atomic hydrogen (H{\\downarrow }) have been presented in the temperature range 0.01-10 K using the Galitskii-Migdal-Feynman formalism. These results include the quantum second virial coefficient, the average total and viscosity cross sections, the viscosity, the diffusion coefficient, and the thermal conductivity. The calculations have been undertaken using three triplet-state potentials: Morse-type, Silvera and Born-Oppenheimer potentials. The Morse potential is less attractive and very simple, but less accurate to describe spin-polarized atomic hydrogen. That explains the differences between it and the other two potentials, which are clearly better. From the results of the average total cross sections, it is concluded the H{\\downarrow } remains a gas even at low temperature. The viscosity, the thermal conductivity, and the diffusion coefficients of H{\\downarrow } increase in all cases with increasing temperature.

  15. Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

    Science.gov (United States)

    Oliva, J.; Ashcroft, N. W.

    1981-01-01

    It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

  16. Fundamental effects of hydrogen on cohesion properties of Cu/W interfaces

    Science.gov (United States)

    Ma, G. C.; Fan, J. L.; Gong, H. R.

    2017-01-01

    First principles calculation is used to investigate the thermodynamic stability of hydrogen at Cu/W interfaces and the effects of hydrogen on cohesion properties of Cu/W interfaces. It is revealed that the solution energies of H atom at the W lattice are more positive than those of H at the Cu/W interface and Cu lattice, suggesting that H atoms in the W lattice should have a tendency to diffuse into the Cu/W interface and Cu lattice. Calculation also shows that the location of interstitial H atom has an important influence on interface cohesion properties, e.g., H atom located just at the very interface area between W and Cu interface layers could dramatically decrease the interface strength of the Cu/W interface, which seems hostile to the performance and lifetime of the Cu/W interface. The derived results are in good agreement with experimental observations in the literature, and are discussed in terms of electronic structures, which could provide a deep understanding to the effects of interstitial H on various cohesion properties of Cu/W interfaces.

  17. Effect of hydrogenation on magnetic properties of heavy transition-metal dichalcogenides

    Science.gov (United States)

    Manchanda, Priyanka; Liou, S.-H.; Enders, Axel; Sellmyer, D. J.; Skomski, Ralph

    Two-dimensional transition-metal dichalcogenides (2D TMDs) are emerging as a unique class of materials because of their underlying fundamental physics and technological applications in electronics, sensors, energy storage, photonics, and spintronics. The outstanding electronic properties of 2D TMDs can be further tuned by various external means, such as control of external electric field, chemical functionalization, alloying, and strain. The electronic and magnetic properties of chemical functionalized 2D TMDs is of special interest. Experimentally, adsorbed fluorine has been shown very recently to create a small magnetic moment of 0.06 emu/g in MoS2 nanosheets. Although several studies as well as review articles on the properties of TMDs have been published in the past few years, Mo and W chalcogenides are most widely studied among the ``beyond-graphene'' 2D TMDs. However, studies of chemical functionalization on TMDs containing heavy TMDs such as Ta and Pt are still infancy. In the present work, we investigate the effect of hydrogenation on the magnetism of PtSe2 monolayers using density-functional theory. We find that the hydrogen induces a magnetic moment of 0.7 µB per unitcell. This work has been supported by ARO, and DOE-BES. This work has been supported by ARO, and DOE-BES.

  18. Analysis of Preparation and Properties on Shape Memory Hydrogenated Epoxy Resin Used for Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Biao Ma

    2017-05-01

    Full Text Available The objective of this investigation is to prepare the shape memory hydrogenated epoxy resin used for asphalt mixtures (SM-HEP-AM and study its properties. The shape memory hydrogenated epoxy resin (SM-HEP is prepared using hydrogenated bisphenol A epoxy resin (AL-3040, polypropylene glycol diglycidylether diacrylate (JH-230, and isophorone diamine (IPDA. The formulations of the SM-HEP-AM are obtained by the linearly fitted method. The thermo-mechanical property, molecular structure, and shape-memory performance of the SM-HEP-AM are studied. The glass-transition temperature (Tg is determined using the differential scanning calorimeter (DSC. The results proved that the Tg level increased when the JH-230 content decreased. The thermo-mechanical property of the SM-HEP-AM is measured by dynamical mechanical analysis (DMA. The storage modulus of the SM-HEP-AM decreased with the increase in the JH-230 content. The above phenomena are attributed to the change in the JH-230 content. The shape memory performance results of the SM-HEP-AM indicate that specimen deformation can completely recover after only several minutes at Tg + 10 °C and Tg + 20 °C. The shape recovery time of the SM-HEP-AM increases with increased JH-230 content, and the change between the shape recovery time and JH-230 content gradually decreased as the temperature increased. The deformation recovery performance of asphalt mixture with and without the SM-HEP-AM (Tg = 40 °C was tested by the deformation recovery test. This was used to prove that the SM-HEP-AM helps to improve the deformation recovery performance of the asphalt mixture.

  19. Nonlinear properties of and nonlinear processing in hydrogenated amorphous silicon waveguides

    DEFF Research Database (Denmark)

    Kuyken, B.; Ji, Hua; Clemmen, S.

    2011-01-01

    We propose hydrogenated amorphous silicon nanowires as a platform for nonlinear optics in the telecommunication wavelength range. Extraction of the nonlinear parameter of these photonic nanowires reveals a figure of merit larger than 2. It is observed that the nonlinear optical properties...... of these waveguides degrade with time, but that this degradation can be reversed by annealing the samples. A four wave mixing conversion efficiency of + 12 dB is demonstrated in a 320 Gbit/s serial optical waveform data sampling experiment in a 4 mm long photonic nanowire....

  20. Electronic, structural and optical properties of hydrogenated silicon nanocrystals: the role of the excited states

    Energy Technology Data Exchange (ETDEWEB)

    Cantele, G.; Ninno, D.; Iadonisi, G. [Coherentia-INFM and Universita di Napoli ' ' Federico II' ' - Dipartimento di Scienze Fisiche, Complesso Universitario Monte S. Angelo, Via Cintia, 80126 Napoli (Italy); Degoli, Elena; Bisi, O.; Ossicini, Stefano [INFM-S' ' 3 and Dipartimento di Scienze e Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia, via Fogliani, 42100 Reggio Emilia (Italy); Luppi, Eleonora; Magri, Rita [INFM-S' ' 3 and Dipartimento di Fisica, Universita di Modena e Reggio Emilia, via Campi 213/A, 41100 Modena (Italy)

    2005-06-01

    In this paper we report on a first-principle calculation of the electronic and structural properties of hydrogenated silicon nanocrystals both in the ground- and in an excited-state configuration. The presence of an electron-hole pair created under excitation is taken into account and its effects on both the electronic spectrum and the cluster geometry are pointed out. The interpretation of the results is done within a four-level model, which also allows the explanation of the experimentally observed Stokes shift. Size-related aspects are also analysed and discussed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Hydrothermal Synthesis and Hydrogen Sensing Properties of Nanostructured SnO2 with Different Morphologies

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2014-01-01

    Full Text Available In this work, nanoscale SnO2 with various geometrical morphologies, including pine needle-like, sphere-like, sheet-like, grape-like nanostructures, was prepared via a facile hydrothermal process. Microstructures and morphologies of all the as-synthesized products were characterized by X-ray diffraction (XRD and field emission scanning electron microscopy (FESEM. Meanwhile, the specific surface areas of the as-prepared SnO2 nanostructures were determined by Brunauer-Emmett-Teller (BET analysis. Gas sensors were fabricated and their gas sensing properties towards hydrogen were systematically investigated. The results indicate pine needle-like SnO2 structure exhibits exclusive better gas sensing performances to hydrogen than the other morphologies, which can be attributed to its novel shape with a large specific surface area. Such an unexpected morphology is a promising candidate for the use of SnO2 as a gas sensing material in future hydrogen sensor applications.

  2. HYDROGEN PEROXIDE PRODUCTION ACTIVITY AND ADHESIVE PROPERTIES OF AEROCOCCI, ISOLATED IN WOMEN

    Directory of Open Access Journals (Sweden)

    Stepanskyi D.O.

    2017-06-01

    Full Text Available Introduction. Antagonistic activity of probiotic microorganisms against other species of bacteria is an important mechanism of their ecology and it is widely used in practice. This activity is inherent in many heme-deficient bacteria, which include aerococci, and can be composed of several components: the production of organic acids, antibiotics, lysozyme, hydrogen peroxide and others. Ability to produce hydrogen peroxide under aerobic conditions and in a state of relative anaerobiosis was established in aerococci. They were divided into strong and weak producers, depending on the amount of peroxides. Lack of data about peroxide-productive ability of aerococci, isolated from the lower genital tract of women, as well as a proven mechanism of hydrogen peroxide excretion in the oxidation of lactic acid, led to need in studying the aerococci hydrogen peroxide production level, to create autobacterial drugs, based on aerococci symbiont strains for sanitation of birth canal. Colonization resistance of the vaginal mucous and normal microflora value depends largely on the degree of adhesion of microbial cells to the mucosal surface. Along with numerous studies of lactobacilli adhesive properties to the vaginal epithelium, there are no data on the adsorption capacity of aerococci to the vaginal epithelial cells. Material and methods. 18 aerococci resident strains and 1 museum strain were explored in total. Presence and quantity of autosymbiont aerococci content in different parts of the birth tract (cervical canal, vagina, external genitalia skin (EGS and perineum was studied in 44 healthy women. Isolation and identification of aerococci from the women body was conducted by the method, taking into account growth on selective indicator medium, growth and biochemical activity in environments with selenium and tellurium salts, lactate oxidase and superoxide dismutase activity. Hydrogen peroxide was determined by iodometric method. Hydrogen peroxide

  3. Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001)

    DEFF Research Database (Denmark)

    Frigge, R.; Hoger, T.; Siemer, B.

    2010-01-01

    Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states of che...

  4. Sound Absorption Properties Of Single-Hole Hollow Polyester Fiber Reinforced Hydrogenated Carboxyl Nitrile Rubber Composites

    Directory of Open Access Journals (Sweden)

    Jie Hong

    2017-09-01

    Full Text Available A series of single-hole hollow polyester fiber (SHHPF reinforced hydrogenated carboxyl nitrile rubber (HXNBR composites were fabricated. In this study, the sound absorption property of the HXNBR/SHHPF composite was tested in an impedance tube, the composite morphology was characterized by scanning electron microscope (SEM, and the tensile mechanical property was measured by strength tester. The results demonstrated that a remarkable change in sound absorption can be observed by increasing the SHHPF content from 0% to 40%. In the composite with 40% SHHPF in 1 mm thickness, the sound absorption coefficient reached 0.671 at 2,500 Hz; the effective bandwidth was 1,800-2,500 Hz for sound absorption coefficient larger than 0.2. But the sound absorption property of the composite deteriorated when the SHHPF content increased to 50% in 1 mm thickness. While with 20% SHHPF proportion, the sound absorption property was improved by increasing the thickness of composites from 1 to 5 mm. Compared with the pure HXNBR of the same thickness, the tensile mechanical property of the composite improved significantly by increasing the SHHPF proportion. As a lightweight composite with excellent sound absorption property, the HXNBR/SHHPF composite has potential practical application value in the fields of engineering.

  5. Opto-electronic properties of adamantane and hydrogen-terminated sila- and germa-adamantane: A comparative study

    Science.gov (United States)

    Marsusi, Farah; Mirabbaszadeh, Kavoos; Ali Mansoori, G.

    2009-06-01

    We present the opto-electronic properties of adamantane (C 10H 16) compared to hydrogen-terminated sila- and germa-adamantane (Si 10H 16 and Ge 10H 16) as calculated by the density functional theory. We have shown that the electronic properties of adamantane in comparison to sila- and germa-adamantane are more affected by hydrogen atoms. Our calculations show that the electron affinity of C 10H 16 is negative, while those of Si 10H 16 and Ge 10H 16 are positive. Electronic properties and optical gaps resulting from hybrid functionals are in close agreement with quantum Monte Carlo results.

  6. Thermodynamic and kinetic properties of hydrogen defect pairs in SrTiO3 from density functional theory

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Bonanos, Nikolaos; Rossmeisl, Jan

    2011-01-01

    A density functional theory investigation of the thermodynamic and kinetic properties of hydrogen–hydrogen defect interactions in the cubic SrTiO3 perovskite is presented. We find a net attraction between two hydrogen atoms with an optimal separation of ∼2.3 Å. The energy gain is ca. 0.33 e...... agreement with the proposed properties of the double hydrogen defect.......V compared to two non-interacting H defects. The main cause of the net attractive potential is elastic defect interactions through lattice deformation. Two possible diffusion paths for the hydrogen defect pair are investigated and are both determined to be faster than the corresponding diffusion path...

  7. Interstellar Hydrogen in Galaxies: Radio observations of neutral hydrogen yield valuable information on the properties of galaxies.

    Science.gov (United States)

    Roberts, M S

    1974-02-01

    Measurement of the 21-cm line radiation originating from the interstellar neutral hydrogen in a galaxy yields information on the total mass and total hydrogen content of the galaxy. The ratio of these two quantities is correlated with structural type in the sense that the later type galaxies contain a higher fraction of their total mass in the form of interstellar hydrogen This ratio is one of the few physical parameters known to correlate with structural type. It need not, however, reflect an evolutionary sequence, such as more hydrogen implying a younger galaxy. Efficiency of conversion of hydrogen to stars can just as easily explain the correlation. Except for the very latest systems, the total mass of a spiral does not appear to be correlated with type. Red shifts of galaxies measured at optical wavelengths and at 21 cm are in excellent agreement. The form of the Doppler expression has been shown to hold over a wavelength range of 5 x 105. All spirals earlier than type Ir which have been studied with adequate resolution show a central minimum in their hydrogen distribution. The region of maximum projected HI surface density occurs at some distance from the center. In the earlier type spirals the optical arms are located in the region of this maximum surface density. In the later type spirals the maximum HI density and prominent optical arms are less well correlated and, at times, are anticorrelated. Detailed studies of the HI distribution and motions within a galaxy require the high relative resolution of beam synthesis arrays. We may expect significant new information from such studies, which are now in progress. Filled-aperture telescopes will supply the necessary observations at zero spacing and vital statistical information on large numbers of galaxies, peculiar systems and groups and clusters of galaxies. The two types of telescope systems will complement one another. In the near future we should have a much better description of spiral galaxies and, we

  8. Ratiometric fluorescent probe with AIE property for monitoring endogenous hydrogen peroxide in macrophages and cancer cells.

    Science.gov (United States)

    Liu, Yong; Nie, Jing; Niu, Jie; Meng, Fangfang; Lin, Weiying

    2017-08-04

    Hydrogen peroxide (H2O2) plays a key role in the progression of human illnesses, such as autoimmune and auto-inflammatory diseases, infectious diseases, diabetes, and cancer, etc. In this work, we have discribed a novel probe, TPE-TLE, which remarkably displayed AIE property and ratiometric fluorescence emission profiles in the presence of H2O2. This ratiometric fluorescent probe with AIE property exhibits outstanding features such as the well-resolved emission peaks, high sensitivity, high selectivity, low cytotoxicity, and good cell-membrane permeability. These excellent attributes enable us to demonstrate the ratiometric imaging of endogenously produced H2O2 in macrophages and cancer cells based on the novel ratiometric probe with AIE property for the first time. By comparing two kinds of cells, it is firstly found that cancer cells should contain much more endogenous H2O2 than macrophages. We expect that TPE-TLE will be useful fluorescent platform for the development of a variety of ratiometric fluorescent probes with AIE property to achieve unique biological applications.

  9. Progress in improving thermodynamics and kinetics of new hydrogen storage materials

    Science.gov (United States)

    Song, Li-fang; Jiang, Chun-hong; Liu, Shu-sheng; Jiao, Cheng-li; Si, Xiao-liang; Wang, Shuang; Li, Fen; Zhang, Jian; Sun, Li-xian; Xu, Fen; Huang, Feng-lei

    2011-06-01

    Hydrogen storage material has been much developed recently because of its potential for proton exchange membrane (PEM) fuel cell applications. A successful solid-state reversible storage material should meet the requirements of high storage capacity, suitable thermodynamic properties, and fast adsorption and desorption kinetics. Complex hydrides, including boron hydride and alanate, ammonia borane, metal organic frameworks (MOFs), covalent organic frameworks (COFs) and zeolitic imidazolate frameworks (ZIFs), are remarkable hydrogen storage materials because of their advantages of high energy density and safety. This feature article focuses mainly on the thermodynamics and kinetics of these hydrogen storage materials in the past few years.

  10. Electrical, optical, and photoluminescence properties of ZnO films subjected to thermal annealing and treatment in hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abdullin, Kh. A.; Gabdullin, M. T. [al-Farabi Kazakh National University, National Nanotechnology Laboratory of Open Type (Kazakhstan); Gritsenko, L. V. [Kazakh National Technical Research University (Kazakhstan); Ismailov, D. V.; Kalkozova, Zh. K. [al-Farabi Kazakh National University, National Nanotechnology Laboratory of Open Type (Kazakhstan); Kumekov, S. E., E-mail: skumekov@mail.ru; Mukash, Zh. O. [Kazakh National Technical Research University (Kazakhstan); Sazonov, A. Yu. [200 University Avenue West, University of Waterloo (Canada); Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2016-08-15

    The photoluminescence and optical absorption spectra and electrical properties of ZnO films grown by the metal–organic chemical vapor deposition and hydrothermal techniques, subjected to heat treatments and plasma treatment in a hydrogen atmosphere, are studied. It is shown that the adsorption of oxygen at grain boundaries upon annealing in an oxidizing atmosphere determines the electrical properties of the films. Vacuum annealing improves the electrical properties of the samples after degradation induced by annealing in air. Treatment in hydrogen plasma passivates surface states at the grain boundaries. The intrinsic photoluminescence intensity after plasma treatment is higher in the case of increased amounts of oxygen adsorbed at grain surfaces upon annealing in air. Surface states involving oxygen and hydrogen atoms are responsible for the high-intensity intrinsic photoluminescence band.

  11. A comparative study of the physicochemical properties of perfluorinated and hydrogenated amphiphiles.

    Science.gov (United States)

    Blanco, Elena; González-Pérez, Alfredo; Ruso, Juan M; Pedrido, Rosa; Prieto, Gerardo; Sarmiento, Félix

    2005-08-01

    In this work we studied and compared the physicochemical properties of perfluorinated (sodium perfluoroheptanoate, C7FONa, and perfluorooctanoate, C8FONa) and hydrogenated (sodium octanoate, C8HONa, decanoate, C10HONa, and dodecanoate, C12HONa) amphiphiles. First, we determined their Krafft points to study the solubility and appropriate temperature range of micellization of these compounds. The critical micelle concentration (cmc) and ionization degree of micellization (beta) as a function of temperature (T) were estimated from conductivity data. Plots of cmc vs T appear to follow the typical U-shaped curve with a minimum T(min). The results show that the surfactants with CF2/CH2 ratio of 1.5 between alkyl chains (C12HONa-C8FONa and C10HONa-C7FONa) have nearly the same minimum value for cmc against temperature. The comparison between the cmc of hydrogenated amphiphiles and the corresponding perfluorinated amphiphiles must be done at this point. Thermodynamic functions of micellization were obtained by applying different theoretical models and choosing the one that best fit our experimental data. Although perfluorinated and hydrogenated amphiphiles present similar thermodynamic behavior, we have found a variation of 1.3 to 1.7 in the CF2/CH2 ratio, which did not remain constant with temperature. In the second part of this study the apparent molar volumes and adiabatic compressibilities were determined from density and ultrasound velocity measurements. Apparent molar volumes at infinite dilution presented the ratio 1.5 between alkyl chains again. However, apparent molar volumes upon micellization for sodium perfluoroheptanoate indicated a different aggregation pattern.

  12. Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

    Science.gov (United States)

    Baldwin, Richard S.

    1987-01-01

    The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

  13. Synthesis and radiosensitization properties of hydrogen peroxide and sodium hyaluronate complex

    Energy Technology Data Exchange (ETDEWEB)

    Rosli, Nur Ratasha Alia Md.; Mohamed, Faizal; Heng, Cheong Kai; Rahman, Irman Abdul; Ahmad, Ainee Fatimah; Mohamad, Hur Munawar Kabir [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia)

    2014-09-03

    Cancer cells which are large in size are resistant towards radiation therapy due to the presence of large amount of anti-oxidative enzymes and hypoxic cancer cells. Thus radiosensitizer agents have been developed to enhance the therapeutic effect of radiotherapy by increasing the sensitivity of these cancer cells towards radiation. This study is conducted to investigate the radiosensitization properties of radiosensitizer complex containing hydrogen peroxide and sodium hyaluronate. Combination with sodium hyaluronate may decrease reactivity of hydrogen peroxide but maintain the oxygen concentration needed for radiosensitizing effect. HepG2 cancer cells are cultured as the mean of test subject. Cancer cell samples which are targeted and not targeted with these radiosensitizers are irradiated with 2Gy single fractionated dose. Results obtained shows that the cancer cells which are not targeted with radiosensitizers has a cell viability of 98.80±0.37% after a time interval of 48 hours and has even repopulated over 100% after a 72 hour time interval. This shows that the cancer cells are resistant towards radiation. However, when the cancer cells are targeted with radiosensitizers prior to irradiation, there is a reduction of cell viability by 25.50±10.81% and 10.30±5.10% at time intervals of 48 and 72 hours respectively. This indicates that through the use of these radiosensitizers, cancer cells are more sensitive towards radiation.

  14. Synthesis and radiosensitization properties of hydrogen peroxide and sodium hyaluronate complex

    Science.gov (United States)

    Rosli, Nur Ratasha Alia Md.; Mohamed, Faizal; Heng, Cheong Kai; Rahman, Irman Abdul; Ahmad, Ainee Fatimah; Mohamad, Hur Munawar Kabir

    2014-09-01

    Cancer cells which are large in size are resistant towards radiation therapy due to the presence of large amount of anti-oxidative enzymes and hypoxic cancer cells. Thus radiosensitizer agents have been developed to enhance the therapeutic effect of radiotherapy by increasing the sensitivity of these cancer cells towards radiation. This study is conducted to investigate the radiosensitization properties of radiosensitizer complex containing hydrogen peroxide and sodium hyaluronate. Combination with sodium hyaluronate may decrease reactivity of hydrogen peroxide but maintain the oxygen concentration needed for radiosensitizing effect. HepG2 cancer cells are cultured as the mean of test subject. Cancer cell samples which are targeted and not targeted with these radiosensitizers are irradiated with 2Gy single fractionated dose. Results obtained shows that the cancer cells which are not targeted with radiosensitizers has a cell viability of 98.80±0.37% after a time interval of 48 hours and has even repopulated over 100% after a 72 hour time interval. This shows that the cancer cells are resistant towards radiation. However, when the cancer cells are targeted with radiosensitizers prior to irradiation, there is a reduction of cell viability by 25.50±10.81% and 10.30±5.10% at time intervals of 48 and 72 hours respectively. This indicates that through the use of these radiosensitizers, cancer cells are more sensitive towards radiation.

  15. The effects of yttrium on the hydrogenation performance and surface properties of a ruthenium-supported catalyst

    Directory of Open Access Journals (Sweden)

    LAITAO LUO

    2005-12-01

    Full Text Available The effects of yttrium on the hydrogenation performance and surface properties of a Ru/sepiolite catalyst were studied. With CO2 methanation and CS2 poisoning as the testing reactons, TPR, TPD, XRD and CO chemisorption as the characterizations, the results showed that the presence of yttrium can increase the hydrogenation activity and anti-poisoning capacity of the Ru/sepiolite catalyst, which is due to a change of surface properties of the Ru/sepiolite. In the process of the catalytic reaction, the adjusting behavior of yttrium for the Ru/sepiolite catalyst aids in increasing the catalytic activity and anti-poisoning capacity of the catalyst.

  16. Physical properties of Fe doped In2O3 magnetic semiconductor annealed in hydrogen at different temperature

    Science.gov (United States)

    Baqiah, H.; Ibrahim, N. B.; Halim, S. A.; Chen, S. K.; Lim, K. P.; Kechik, M. M. Awang

    2016-03-01

    The effects of hydrogen-annealing at different temperatures (300, 400, 500 and 600 °C) on physical properties of In2-xFexO3 (x=0.025) thin film were investigated. The structural measurement using XRD shows that the film has a single In2O3 phase structure when annealed in hydrogen at 300-500 °C, however when annealed in hydrogen at 600 °C the film has a mixed phase structure of In2O3 and In phases. The electrical measurements show that the carrier concentrations of the films decrease with the increase of hydrogen-annealing temperature in the range 300-500 °C. The optical band gap of the films decreases with increasing hydrogen-annealing temperatures. The saturation magnetisation, Ms, and coercivity of films increase with the increment of hydrogen annealing temperature. The film annealed at 300 °C has the lowest resistivity, ρ=0.03 Ω cm, and the highest carrier concentrations, n=6.8×1019 cm-3, while film annealed at 500 °C has both good electrical (ρ=0.05 Ω.cm and n=2.2×1019 cm-3) and magnetic properties, Ms=21 emu/cm-3.

  17. Hydrogenated polyisoprene-silica nanoparticles and their applications for nanocomposites with enhanced mechanical properties and thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Kongsinlark, Anong [Faculty of Science, Chulalongkorn University, Program in Petrochemistry and Polymer Science (Thailand); Rempel, Garry L., E-mail: grempel@uwaterloo.ca [University of Waterloo, Department of Chemical Engineering (Canada); Prasassarakich, Pattarapan, E-mail: ppattara@chula.ac.th [Faculty of Science, Chulalongkorn University, Department of Chemical Technology (Thailand)

    2013-05-15

    Hydrogenated polyisoprene (HPIP)-SiO{sub 2} nanocomposites were synthesized via differential microemulsiion polymerization followed by diimide hydrogenation. First, the isoprene monomer was polymerized on the silane treated nanosilica by differential microemulsion polymerization to obtain polyisoprene (PIP)-SiO{sub 2} nanoparticles with a particle size of 43 nm. PIP-SiO{sub 2} latex was subsequently hydrogenated at the carbon-carbon double bonds by diimide reduction in the presence of hydrazine and hydrogen peroxide with boric acid as promotor to provide HPIP-SiO{sub 2} nanocomposites. Core-shell morphology consisting of silica as the nano-core encapsulated by HPIP as the nano-shell was formed. The highest hydrogenation degree of 98 % was achieved at a ratio of hydrogen peroxide to hydrazine of 1.5:1. The nanosized HPIP-SiO{sub 2} at 98 % hydrogenation showed a maximum degradation temperature of 521 Degree-Sign C resulting in excellent thermal stability, compared with unfilled PIP (387 Degree-Sign C). A new nanocomposite of HPIP-SiO{sub 2} could be used as a novel nanofiller in natural rubber. Consequently, HPIP-SiO{sub 2}/NR composites had improved mechanical properties and exhibited a good retention of tensile strength after thermal aging and good resistance toward ozone exposure.

  18. Study of electronic and optical properties of two-layered hydrogenated aluminum nitrate nanosheet

    Science.gov (United States)

    Faghihzadeh, Somayeh; Shahtahmasebi, Nasser; Rezaee Roknabadi, Mahmood

    2017-09-01

    First principle calculations based on density functional theory using GW approximation and two particle Bethe-Salpeter equation with electron-hole effect were performed to investigate electronic structure and optical properties of two-layered hydrogenated AlN. According to many body green function due to decrease in dimension and considering electron-electron effect, direct (indirect) band gap change from 2 (1.01) eV to 4.83 (3.62) eV. The first peak in imaginary part of dielectric function was observed in parallel direction to a plane obtaining 3.4 was achieved by bound exciton states possess 1.39 eV. The first absorption peak was seen in two parallel and perpendicular directions to a plane which are in UV region.

  19. Tunable Electrical Properties of Vanadium Oxide by Hydrogen-Plasma-Treated Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Helen Hejin Park

    2017-04-01

    Full Text Available In this study, a plasma-modified process was developed to control the electrical properties of atomic layer deposition (ALD-grown vanadium dioxide (VO2, which is potentially useful for applications such as resistive switching devices, bolometers, and plasmonic metamaterials. By inserting a plasma pulse with varying H2 gas flow into each ALD cycle, the insulator-to-metal transition (IMT temperature of postdeposition-annealed crystalline VO2 films was adjusted from 63 to 78 °C. Film analyses indicate that the tunability may arise from changes in grain boundaries, morphology, and compositional variation despite hydrogen not remaining in the annealed VO2 films. This growth method, which enables a systematic variation of the electronic behavior of VO2, provides capabilities beyond those of the conventional thermal ALD and plasma-enhanced ALD.

  20. Preparation and hydrogen storage properties of nanocrystalline TiFe synthesized by mechanical alloying

    Directory of Open Access Journals (Sweden)

    V.Yu. Zadorozhnyy

    2017-02-01

    Full Text Available In this research, the mechanism of mechanical alloying (MA synthesis of TiFe intermetallic compound (IMC from individual components Ti and Fe has been studied. The partition coefficient of the apparent diffusion and the reaction rate constant during MA solid-state synthesis of the TiFe intermetallic compound in a planetary ball mill have been estimated. The results indicate that the apparent diffusion coefficient is close to 10–11 cm2/s that is approximately one order higher than the conventional high temperature diffusion coefficient. The reaction rate constant is close to 1.75·10−6. The relation between the structure and the hydrogen storage properties of MA synthesized IMC TiFe have been briefly discussed.

  1. Estimating explosion properties of normal hydrogen-rich core-collapse supernovae

    Science.gov (United States)

    Pejcha, Ondrej

    2017-08-01

    Recent parameterized 1D explosion models of hundreds of core-collapse supernova progenitors suggest that success and failure are intertwined in a complex pattern that is not a simple function of the progenitor initial mass. This rugged landscape is present also in other explosion properties, allowing for quantitative tests of the neutrino mechanism from observations of hundreds of supernovae discovered every year. We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of normal hydrogen-rich core-collapse supernovae based on their photometric measurements and expansion velocities. We construct SED and bolometric light curves, determine explosion energies, ejecta and nickel masses while taking into account all uncertainties and covariances of the model. We describe the efforts to compare the inferences to the predictions of the neutrino mechanim. The model can be adapted to include more physical assumptions to utilize primarily photometric data coming from surveys such as LSST.

  2. Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1998-09-01

    A systematic study has been initiated at Argonne National Laboratory to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, the principal effort has focused on the V-4Cr-4Ti alloy of heat identified as BL-71; however other alloys (V-5Cr-5Ti alloy of heats BL-63, and T87, plus V-4Cr-4Ti alloy from General Atomics [GA]) are also being evaluated. Other variables of interest are the effect of initial grain size on the tensile behavior of the alloys. Experiments conducted on specimens of various V-Cr-Ti alloys exposed to pH{sub 2} levels of 0.01 and 3 {times} 10{sup {minus}6} torr showed negligible effect of H{sub 2} on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed to 1.0 torr H{sub 2} pressure. Preliminary data from sequential exposures of the materials to low-pO{sub 2} and several low-pH{sub 2} environments did not reveal an adverse effect on the maximum engineering stress or on uniform and total elongation. Further, tests in H{sub 2} environments on specimens annealed at different temperatures showed that grain-size variation by a factor of {approx}2 had little or no effect on tensile properties.

  3. An analysis of quantum effects on the thermodynamic properties of cryogenic hydrogen using the path integral method.

    Science.gov (United States)

    Nagashima, H; Tsuda, S; Tsuboi, N; Koshi, M; Hayashi, K A; Tokumasu, T

    2014-04-07

    In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density-temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure-volume-temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases.

  4. Thermoresponsive Poly(Ionic Liquid)s in Aqueous Salt Solutions: Salting-Out Effect on Their Phase Behavior and Water Absorption/Desorption Properties.

    Science.gov (United States)

    Okafuji, Akiyoshi; Kohno, Yuki; Ohno, Hiroyuki

    2016-07-01

    Here, a thermoresponsive phase behavior of polymerized ionic liquids (PILs) composed of poly([tri-n-alkyl(vinylbenzyl)phosphonium]chloride) (poly([Pnnn VB ]Cl) is reported, where n (the number of carbon atoms of an alkyl chain) = 4, 5, or 6 after mixing with aqueous sodium chloride solutions. Both monomeric [P555VB ]Cl and the resulting poly([P555VB ]Cl) linear homopolymer show a lower critical solution temperature (LCST)-type phase behavior in aq. NaCl solutions. The phase transition temperature of the PIL shifts to lower value by increasing concentration of NaCl. Also the swelling degree of cross-linked poly([P555VB ]Cl) gel decreases by increasing NaCl concentration, clearly suggesting the "salting-out" effect of NaCl results in a significant dehydration of the poly([P555VB ]Cl) gel. The absorbed water in the PIL gel is desorbed by moderate heating via the LCST behavior, and the absolute absorption/desorption amount is improved by copolymerization of [P555VB ]Cl with more hydrophilic [P444VB ]Cl monomer. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. HYDROGEN PEROXIDE PRODUCTION ACTIVITY AND ADHESIVE PROPERTIES OF AEROCOCCI, ISOLATED IN WOMEN

    National Research Council Canada - National Science Library

    Stepanskyi D.O; Kremenchutsky G.M; Chuyko V.I; Koshova I.P; Khomiak O.V; Krushynska T.Y

    2017-01-01

    ...: the production of organic acids, antibiotics, lysozyme, hydrogen peroxide and others. Ability to produce hydrogen peroxide under aerobic conditions and in a state of relative anaerobiosis was established in aerococci...

  6. Impact of Materials Processing on Microstructural Evolution and Hydrogen Isotope Storage Properties of Pd-Rh Alloy Powders.

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Joshua K [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    Cryomilled Pd - 10Rh was investiga ted as potential solid - state storage material of hydrogen. Pd - 10Rh was first atomized, and then subsequently cryomilled. The cryomilled Pd - 10Rh was then examined using microstructural characterization techniques including op tical microscopy, electron microscopy, and X - ray diffraction. Pd - 10Rh particles were significantly flattened, increasing the apparent surface area. Microstructural refinement was observed in the cryomilled Pd - 10Rh, generating grains at the nanom etric scale through dislocation - based activity. Hydrogen sorption properties were also characterized, generating both capacity as well as kinetics measurements. It was found that the microstructural refinement due to cryomilling did not play a significant role on hyd rogen sorption properties until the smallest grain size (on the order of %7E25 nm) was achieved. Additionally, the increased surface area and other changes in particle morphology were associated with cryomilling changed the kinetics of hydrogen absorption.

  7. Syntheses and properties of several metastable and stable hydrides derived from intermetallic compounds under high hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Filipek, S.M., E-mail: sfilipek@unipress.waw.pl [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Paul-Boncour, V. [ICMPE-CMTR, CNRS-UPEC, 2-8 rue Henri Dunant, 94320 Thiais (France); Liu, R.S. [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Jacob, I. [Unit Nuclear Eng., Ben Gurion University of the Negev, Beer-Sheva (Israel); Tsutaoka, T. [Dept. of Sci. Educ., Grad. School of Educ., Hiroshima University, Hiroshima (Japan); Budziak, A. [Institute of Nuclear Physics PAS, 31-342 Kraków (Poland); Morawski, A. [Institute of High Pressure Physics PAS, ul. Sokolowska 29, 01-142 Warsaw (Poland); Sugiura, H. [Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027 (Japan); Zachariasz, P. [Institute of Electron Technology Cracow Division, ul. Zablocie 39, 30-701 Krakow (Poland); Dybko, K. [Institute of Physics, PAS, 02-668 Warsaw (Poland); Diduszko, R. [Tele and Radio Research Institute, ul. Ratuszowa 11, Warsaw (Poland)

    2016-12-01

    Brief summary of our former work on high hydrogen pressure syntheses of novel hydrides and studies of their properties is supplemented with new results. Syntheses and properties of a number of hydrides (unstable, metastable or stable in ambient conditions) derived under high hydrogen pressure from intermetallic compounds, like MeT{sub 2}, MeNi{sub 5}, Me{sub 7}T{sub 3}, Y{sub 6}Mn{sub 23} and YMn{sub 12} (where Me = zirconium, yttrium or rare earth; T = transition metal) are presented. Stabilization of ZrFe{sub 2}H{sub 4} due to surface phenomena was revealed. Unusual role of manganese in hydride forming processes is pointed out. Hydrogen induced phase transitions, suppression of magnetism, antiferromagnetic-ferromagnetic and metal-insulator or semimetal-metal transitions are described. Equations of state (EOS) of hydrides submitted to hydrostatic pressures up to 30 GPa are presented and discussed.

  8. Carbon support effects on the hydrogen storage properties of LiBH4 nanoparticles: a first-principles study

    NARCIS (Netherlands)

    Hazrati, Ebrahim; Brocks, G.; de Wijs, Gilles A.

    2014-01-01

    LiBH4 nanoparticles confined in nanoporous carbon materials show improved hydrogen storage properties. Using density functional theory calculations, we study how the thermodynamics of the decomposition reactions of LiBH4 nanoparticles is affected by the chemical interactions between the reactant or

  9. Effect of a DC external electric field on the properties of a nonuniform microwave discharge in hydrogen at reduced pressures

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, Yu. A., E-mail: lebedev@ips.ac.ru; Krashevskaya, G. V.; Tatarinov, A. V.; Titov, A. Yu.; Epshtein, I. L. [Russian Academy of Sciences, Topchiev Institute of Petrochemical Synthesis (Russian Federation)

    2017-01-15

    The effect of a dc external electrical field on the properties of a highly nonuniform electrode microwave discharge in hydrogen at a pressure of 1 Torr was studied using optical emission spectroscopy and selfconsistent two-dimensional simulations. It is shown that the negative voltage applied to the antenna electrode with respect to the grounded chamber increases the discharge radiation intensity, while the positive voltage does not affect the discharge properties. The simulation results agree well with the experimental data.

  10. Hydrogen bond networks determine emergent mechanical and thermodynamic properties across a protein family

    Directory of Open Access Journals (Sweden)

    Dallakyan Sargis

    2008-08-01

    Full Text Available Abstract Background Gram-negative bacteria use periplasmic-binding proteins (bPBP to transport nutrients through the periplasm. Despite immense diversity within the recognized substrates, all members of the family share a common fold that includes two domains that are separated by a conserved hinge. The hinge allows the protein to cycle between open (apo and closed (ligated conformations. Conformational changes within the proteins depend on a complex interplay of mechanical and thermodynamic response, which is manifested as an increase in thermal stability and decrease of flexibility upon ligand binding. Results We use a distance constraint model (DCM to quantify the give and take between thermodynamic stability and mechanical flexibility across the bPBP family. Quantitative stability/flexibility relationships (QSFR are readily evaluated because the DCM links mechanical and thermodynamic properties. We have previously demonstrated that QSFR is moderately conserved across a mesophilic/thermophilic RNase H pair, whereas the observed variance indicated that different enthalpy-entropy mechanisms allow similar mechanical response at their respective melting temperatures. Our predictions of heat capacity and free energy show marked diversity across the bPBP family. While backbone flexibility metrics are mostly conserved, cooperativity correlation (long-range couplings also demonstrate considerable amount of variation. Upon ligand removal, heat capacity, melting point, and mechanical rigidity are, as expected, lowered. Nevertheless, significant differences are found in molecular cooperativity correlations that can be explained by the detailed nature of the hydrogen bond network. Conclusion Non-trivial mechanical and thermodynamic variation across the family is explained by differences within the underlying H-bond networks. The mechanism is simple; variation within the H-bond networks result in altered mechanical linkage properties that directly affect

  11. Evaluation of one-dimensional potential energy surfaces for prediction of spectroscopic properties of hydrogen bonds in linear bonded complexes.

    Science.gov (United States)

    Jouypazadeh, Hamidreza; Farrokhpour, Hossein; Solimannejad, Mohammad

    2017-05-01

    This work evaluated the reliability of the one-dimensional potential energy surface for calculating the spectroscopic properties (rovibrational constants and rotational line energies) of hydrogen bonds in linear bonded complexes by comparing theoretical results with the corresponding experimental results. For this purpose, two hydrogen bonded complexes were selected: the HCN···HCN homodimer and the HCN···HF heterodimer. The one-dimensional potential energy surfaces related to the hydrogen bonds in these complexes were calculated using different computational methods and basis sets. The calculated potential curve of each complex was fitted to an analytical one-dimensional potential function to obtain the potential parameters. The obtained analytical potential function of each complex was used in a two-particle Schrödinger equation to obtain the rovibrational energy levels of the hydrogen bond. Using the calculated rovibrational levels, the rovibrational spectra and constants of each complex were calculated and compared with experimental data available from the literature. Compared with experimental data, the calculated one-dimensional potential energy surface at the QCISD/aug-cc-pVDZ level of theory was found to predict the spectroscopic properties of hydrogen bonds better than the potential curves obtained using other computational methods, especially for the HCN···HCN homodimer complex. Generally, the results obtained for the HCN···HCN homodimer complex were closer to experimental data than those obtained for the HCN···HF heterodimer complex. The investigation performed in this work showed that the one-dimensional potential curve related to the hydrogen bond between two linear molecules can be used to predict the spectroscopic constants of hydrogen bonds. Graphical abstract Potential energy curves of HCN···HCN and HCN···HF complexes calculated at the different computational levels.

  12. Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM).

    Science.gov (United States)

    Netzel, Jeanette; van Smaalen, Sander

    2009-10-01

    Charge densities have been determined by the Maximum Entropy Method (MEM) from the high-resolution, low-temperature (T approximately 20 K) X-ray diffraction data of six different crystals of amino acids and peptides. A comparison of dynamic deformation densities of the MEM with static and dynamic deformation densities of multipole models shows that the MEM may lead to a better description of the electron density in hydrogen bonds in cases where the multipole model has been restricted to isotropic displacement parameters and low-order multipoles (l(max) = 1) for the H atoms. Topological properties at bond critical points (BCPs) are found to depend systematically on the bond length, but with different functions for covalent C-C, C-N and C-O bonds, and for hydrogen bonds together with covalent C-H and N-H bonds. Similar dependencies are known for AIM properties derived from static multipole densities. The ratio of potential and kinetic energy densities |V(BCP)|/G(BCP) is successfully used for a classification of hydrogen bonds according to their distance d(H...O) between the H atom and the acceptor atom. The classification based on MEM densities coincides with the usual classification of hydrogen bonds as strong, intermediate and weak [Jeffrey (1997). An Introduction to Hydrogen Bonding. Oxford University Press]. MEM and procrystal densities lead to similar values of the densities at the BCPs of hydrogen bonds, but differences are shown to prevail, such that it is found that only the true charge density, represented by MEM densities, the multipole model or some other method can lead to the correct characterization of chemical bonding. Our results do not confirm suggestions in the literature that the promolecule density might be sufficient for a characterization of hydrogen bonds.

  13. The effect of slightly faster strain rates and internal hydrogen on uranium-0. 8 weight percent titanium alloy mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Bird, E.L.

    1990-10-10

    Mechanical testing of uranium-0.8 wt % titanium (U-0.8 wt % Ti) alloys can affect the outcome of mechanical properties, primarily ductility, by varying the crosshead velocity, which changes the strain rate. However, most specifications that govern mechanical properties of this alloy reference ASTM E-8, which limits the speed to 0.5 in./in. of gage length per minute. Our current procedure for testing U-0.8 Ti is not at the maximum speed permitted in ASTM E-8, so an experiment was designed to evaluate the effect of maximizing the crosshead velocity per ASTM E-8. In order to create a fair assessment, tensile specimens were prepared that were low in internal hydrogen (0.02 ppM) and higher in internal hydrogen (0.36 ppM). External hydrogen effects were minimized by testing in a controlled environment that contained less than 10% relative humidity. Test results showed that for the low hydrogen test group, increasing the crosshead velocity caused a significant increase in reduction in area (RA), but not in elongation. For the higher hydrogen test group, increasing the speed resulted in a significant increase in RA and an increase, though not statistically significant, in elongation. Of equal importance was an observation that strongly suggests a correlation between material defects, like inclusion clusters, and higher hydrogen content, especially at the slower strain rate that would explain the erratic behavior in ductile properties associated with this alloy. As a result of this study, increasing the crosshead velocity to 0.32 in./min is recommended for mechanical testing of U-0.8 Ti alloys. 9 refs., 4 figs., 5 tabs.

  14. Experimental study on desorption of soluble matter as influenced by cations in static water

    Directory of Open Access Journals (Sweden)

    Wen-sheng XU

    2015-10-01

    Full Text Available With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca2+ and H+ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca2+ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.

  15. Ice XVII as a Novel Material for Hydrogen Storage

    Directory of Open Access Journals (Sweden)

    Leonardo del Rosso

    2017-02-01

    Full Text Available Hydrogen storage is one of the most addressed issues in the green-economy field. The latest-discovered form of ice (XVII, obtained by application of an annealing treatment to a H 2 -filled ice sample in the C 0 -phase, could be inserted in the energy-storage context due to its surprising capacity of hydrogen physisorption, when exposed to even modest pressure (few mbars at temperature below 40 K, and desorption, when a thermal treatment is applied. In this work, we investigate quantitatively the adsorption properties of this simple material by means of spectroscopic and volumetric data, deriving its gravimetric and volumetric capacities as a function of the thermodynamic parameters, and calculating the usable capacity in isothermal conditions. The comparison of ice XVII with materials with a similar mechanism of hydrogen adsorption like metal-organic frameworks shows interesting performances of ice XVII in terms of hydrogen content, operating temperature and kinetics of adsorption-desorption. Any application of this material to realistic hydrogen tanks should take into account the thermodynamic limit of metastability of ice XVII, i.e., temperatures below about 130 K.

  16. Improved metal hydride technology for the storage of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Sapru, K.; Ming, L.; Ramachandran, S. [Energy Conversion Devices, Inc., Troy, MI (United States)] [and others

    1995-09-01

    Low cost, high density storage of hydrogen will remove the most serious barrier to large-scale utilization of hydrogen as a non-polluting, zero-emission fuel. An important challenge for the practical use of Mg-based, high capacity hydrogen storage alloys has been the development of a low-cost, bulk production technique. Two difficulties in preparation of Mg-based alloys are the immiscibility of Mg with many transition metals and the relatively high volatility of Mg compared to many transition metals. These factors preclude the use of conventional induction melting techniques for the Mg-based alloy preparation. A mechanical alloying technique, in which Mg immiscibility and volatility do not present a problem, was developed and shows great promise for production of Mg-based alloys. A number of Mg-based alloys were prepared via modified induction melting and mechanical alloying methods. The alloys were tested for gas phase hydrogen storage properties, composition, structure and morphology. The mechanically alloyed samples are multi-component, multi-phase, highly disordered materials in their as-prepared state. These unoptimized alloys have shown reversible H-storage capacity of more than 5 wt.% hydrogen. After 2000 absorption/desorption cycles, the alloys show no decline in storage capacity or desorption kinetics. The alloys have also demonstrated resistance to CH{sub 4} and CO poisoning in preliminary testing. Upon annealing, with an increase in crystallinity, the H-storage capacity decreases, indicating the importance of disorder.

  17. Sorption and desorption of diuron in Oxisol under biochar application

    Directory of Open Access Journals (Sweden)

    Fabiano André Petter

    Full Text Available ABSTRACT The objective of this study was to verify the kinetics of sorption and desorption of diuron in an Oxisol under application of biochar. The samples were collected in a field experiment conducted in randomized design blocks consisted of 2 base fertilization levels (0 and 400 kg∙ha−1 NPK 00-20-20 fertilizer formula and 3 doses of biochar (0, 8 and 16 Mg∙ha−1. In the evaluation of sorption and desorption, Batch Equilibrium method was used. The kinetics of sorption and desorption of diuron, total organic carbon, fulvic acid, humic acid and humin, pH and partition coefficient to organic carbon were evaluated. The Freundlich isotherm was adjusted appropriately to describe diuron sorption kinetics in all the studied treatments. The application of biochar provided increment in the sorption (Kf and reduction in the desorption of diuron in 64 and 44%, respectively. This effect is attributed to the biochar contribution to the total organic carbon and C-humin and of these to diuron through hydrophobic interactions and hydrogen bonds. The positive correlation between the partition coefficient to organic carbon and Kf confirms the importance of soil organic compartment in the sorption of diuron. There was no competition of NPK fertilizer for the same sorption site of diuron. The increase and reduction in sorption and desorption, respectively, show that the application of biochar is an important alternative for the remediation of soil leaching of diuron, especially in sandy soils.

  18. Thermodynamics of Hydrogen in Confined Lattice

    OpenAIRE

    Xiao, Xin

    2016-01-01

    Three of the most important questions concerning hydrogen storage in metals are how much hydrogen can be absorbed, how fast it can be absorbed (or released) and finally how strongly the hydrogen is bonded. In transition metals hydrogen occupies interstitial sites and the absorption as well as desorption of hydrogen can be fast. The enthalpy of the hydride formation is determined by the electronic structure of the absorbing material, which determines the amount of energy released in the hydrog...

  19. Effect of desorption and recombination on texture development in hydrogenation–disproportionation–desorption–recombination processed Nd–Fe–B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hoon; An, Byeong-Seon [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of); Cha, Hee-Ryoung [Powder & Ceramics Division, Korea Institute of Materials Science, Changwon 51508 (Korea, Republic of); School of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Lee, Jung-Goo, E-mail: jglee36@kims.re.kr [Powder & Ceramics Division, Korea Institute of Materials Science, Changwon 51508 (Korea, Republic of); Kwon, Hae-Woong, E-mail: hwkwon@pknu.ac.kr [Department of Materials Science and Engineering, Pukyong National University, Busan 48513 (Korea, Republic of); Yang, Cheol-Woong, E-mail: cwyang@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of)

    2016-07-05

    The microstructural evolution of Nd–Fe–B magnets during a hydrogenation–disproportionation–desorption–recombination (HDDR) process was investigated, with particular focus on the effects of the desorption–recombination (DR) stage of the process. Samples that went through the DR process under different conditions were compared to examine the texture development during the reaction. Even though the same hydrogenation–disproportionation (HD) treatment was carried out on all samples before the DR reaction, variations in conditions of the latter significantly affected the development of texture in the samples. In consideration of the microstructural evolution, magnetic properties, and thermodynamics, nucleation of recombined Nd{sub 2}Fe{sub 14}B grains was found to occur not only at the NdH{sub 2}/Fe{sub 2}B interfaces but also at the NdH{sub 2}/α-Fe interfaces, and it was affected by the desorption of hydrogen. Preferential growth of nuclei at the NdH{sub 2}/Fe{sub 2}B interfaces, which led to a highly textured Nd{sub 2}Fe{sub 14}B phase, could be induced by slow desorption and recombination with a low driving force. Hydrogen desorption at a slower rate was important for achieving high magnetic anisotropy in the HDDR-processed Nd–Fe–B powders. - Highlights: • The DR condition significantly affected magnetic anisotropy of HDDR powder. • Mechanism of texture development during the DR stage was suggested. • Recombined Nd{sub 2}Fe{sub 14}B could be nucleated at both NdH{sub 2}/Fe{sub 2}B and NdH{sub 2}/α-Fe interfaces. • Hydrogen pressure during DR reaction affects the preference of nucleation site. • Slow DR process is important for high magnetic anisotropy.

  20. NATO International Symposium on the Electronic Structure and Properties of Hydrogen in Metals

    CERN Document Server

    Satterthwaite, C

    1983-01-01

    Hydrogen is the smallest impurity atom that can be implanted in a metallic host. Its small mass and strong interaction with the host electrons and nuclei are responsible for many anomalous and interesting solid state effects. In addition, hydrogen in metals gives rise to a number of technological problems such as hydrogen embrittlement, hydrogen storage, radiation hardening, first wall problems associated with nuclear fusion reactors, and degradation of the fuel cladding in fission reactors. Both the fundamental effects and applied problems have stimulated a great deal of inter­ est in the study of metal hydrogen systems in recent years. This is evident from a growing list of publications as well as several international conferences held in this field during the past decade. It is clear that a fundamental understanding of these problems re­ quires a firm knowledge of the basic interactions between hydrogen, host metal atoms, intrinsic lattice defects and electrons. This understanding is made particularly di...

  1. Thermodynamic Properties of Hydrogen + Tetra-n-Butyl Ammonium Bromide Semi-Clathrate Hydrate

    Directory of Open Access Journals (Sweden)

    Shunsuke Hashimoto

    2010-01-01

    Full Text Available Thermodynamic stability and hydrogen occupancy on the hydrogen + tetra-n-butyl ammonium bromide semi-clathrate hydrate were investigated by means of Raman spectroscopic and phase equilibrium measurements under the three-phase equilibrium condition. The structure of mixed gas hydrates changes from tetragonal to another structure around 95 MPa and 292 K depending on surrounding hydrogen fugacity. The occupied amount of hydrogen in the semi-clathrate hydrate increases significantly associated with the structural transition. Tetra-n-butyl ammonium bromide semi-clathrate hydrates can absorb hydrogen molecules by a pressure-swing without destroying the hydrogen bonds of hydrate cages at 15 MPa or over.

  2. Femtosecond laser pulse induced desorption: A molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lončarić, Ivor, E-mail: ivor.loncaric@gmail.com [Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Alducin, Maite [Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain); Saalfrank, Peter [Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam (Germany); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain); Juaristi, J. Iñaki [Departamento de Física de Materiales, Facultad de Químicas, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián (Spain); Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain)

    2016-09-01

    In recent simulations of femtosecond laser induced desorption of molecular oxygen from the Ag(110) surface, it has been shown that depending on the properties (depth and electronic environment) of the well in which O{sub 2} is adsorbed, the desorption can be either induced dominantly by hot electrons or via excitations of phonons. In this work we explore whether the ratios between the desorption yields from different adsorption wells can be tuned by changing initial surface temperature and laser pulse properties. We show that the initial surface temperature is an important parameter, and that by using low initial surface temperatures the electronically mediated process can be favored. In contrast, laser properties seem to have only a modest influence on the results.

  3. Hydrogen Sorption Properties of the Intermetallic Mg2Ni Obtained by Using a Simoloyer Ball Milling

    Directory of Open Access Journals (Sweden)

    Bormann R.

    2010-07-01

    Full Text Available Intermetallic Mg2Ni was produced from elemental powder blends by mechanical alloying in a batch scale using a rotary horizontal mill (Simoloyer. Fast hydrogenation kinetics are obtained: 2.2 wt.% of hydrogen is absorbed within 10 minutes at 300 °C. Hydrogen sorption kinetics were further improved by adding Pd (1 mol% powder as a catalyst during ball milling. Crack formation and concomitant particle size reduction was observed by scanning electron microscopy after hydrogen cycling, which is attributed to internal stresses in the particles.

  4. Effects of doping FeCl3 on hydrogen storage properties of Li-N-H system

    Directory of Open Access Journals (Sweden)

    Weijin Zhang

    2017-02-01

    Full Text Available The effects of doping FeCl3 on the LiNH2−2LiH system were investigated systematically. FeCl3 was prior to react with LiH during ball milling their mixtures. The metallic Fe, which is generated from metathesis reaction between FeCl3 and LiH, plays an important role on improving the dehydrogenation kinetics of LiNH2−2LiH system. The results indicated that the dehydrogenation peak and ending temperatures of the doped 1 mol% FeCl3 sample shifted to low temperatures, and the dehydrogenation active energy changed from 102.45 kJ/mol to 87.52 kJ/mol. While increasing the amount of FeCl3, an excess of LiCl, the by-product of metathesis reaction between FeCl3 and LiH, can stabilize LiNH2 and thus hinder hydrogen desorption. The dehydrogenation product is a new solid cubic phase solution of lithium imide-chloride. The high limit of the solid solution of LiCl and Li2NH is near the molar ratio of 1:1.

  5. Hydrogen peroxide effects on root hydraulic properties and plasma membrane aquaporin regulation in Phaseolus vulgaris.

    Science.gov (United States)

    Benabdellah, Karim; Ruiz-Lozano, Juan Manuel; Aroca, Ricardo

    2009-08-01

    In the last few years, the role of reactive oxygen species as signaling molecules has emerged, and not only as damage-related roles. Here, we analyzed how root hydraulic properties were modified by different hydrogen peroxide (H2O2) concentrations applied exogenously to the root medium. Two different experimental setups were employed: Phaseolus vulgaris plants growing in hydroponic or in potted soils. In both experimental setups, we found an increase of root hydraulic conductance (L) in response to H2O2 application for the first time. Twenty millimolar was the threshold concentration of H2O2 for observing an effect on L in the soil experiment, while in the hydroponic experiment, a positive effect on L was observed at 0.25 mM H2O2. In the hydroponic experiment, a correlation between increased L and plasma membrane aquaporin amount and their root localization was observed. These findings provide new insights to study how several environmental factors modify L.

  6. Ion Fluence and Energy Effects on the Optical Properties of SS Mirrors Bombarded by Hydrogen Ions

    Energy Technology Data Exchange (ETDEWEB)

    Bardamid, A.F. [T. Shevchenko National Univ., Kiev (Ukraine); Belyaeva, A.I. [National Technical Univ. KhPI, Kharkov (Ukraine); Bondarenko, V.N. [NSC KIPT, Kharkov (Ukraine)] (and others)

    2003-04-01

    The effects of hydrogen ion (H{sub 3}{sup +}) bombardment on the optical properties of polycrystal stainless steel (SS) mirrors were investigated. Ellipsometry, profilometry, scanning electron microscopy, angle distribution of scattered light, and spectral reflectance were used to characterize the surfaces. Results for the bombardment of SS mirrors with ions of fixed energy (0.3, 0.65 and 1.5 keV/H), with ion flux density (0.5-2) x 10{sup 20} H/m{sup 2}/s up to fluences of (1.1-4.3) x 10{sup 24} H/m{sup 2} are presented. The data show that the surface roughness rises with both increasing ion energy and ion fluence, and that surface roughening leads to an increase of the scattered light with a corresponding decrease of reflectance at normal incidence. The thickness of the apparent layer, obtained by ellipsometry, was found to rise with increasing ion energy at fixed ion fluence and with increasing ion fluence at fixed ion energy. Possible mechanisms for the ion energy effect on the degradation rate of stainless steel mirrors and the origin of the apparent layer are discussed.

  7. Barrier properties of hydrogenated acrylonitrile-butadiene rubber composites containing modified layered aluminosilicates

    Science.gov (United States)

    Krzemińska, S.; Rzymski, W. M.

    2011-12-01

    The resistance to permeation by the selected solvents of flat membranes made of cured hydrogenated acrylonitrile-butadiene rubber (HNBR) materials without any fillers and containing 5 phr of layered aluminosilicate nanofiller (bentonite), modified with various types of ammonium salts or N330 type carbon black, was investigated. The barrier properties were assessed on the basis of the breakthrough time of a liquid with low (cyclohexane) or average (butyl acetate) thermodynamic affinity to HNBR, determined according to EN 6529:2001, through a cured elastomer sample. The addition of bentonite, irrespectively of the method of modification of its particles, was found to increase the cured HNBR breakthrough time by 20 - 35 % in the case of slowly permeating non-polar cyclohexane, and by 50 - 130 % in the case of polar butyl acetate permeating more rapidly, in comparison with the barrier material containing no filler. The layered aluminosilicate nanofillers increased the breakthrough time of the material sample for both the tested solvents. In particular, the breakthrough time for polar butyl acetate was even longer than for conventional carbon black. Additionally, the increase of the breakthrough time was observed to depend on the modifier of bentonite particle surface.

  8. Ion Fluence and Energy Effects on the Optical Properties of SS Mirrors Bombarded by Hydrogen Ions

    Science.gov (United States)

    Bardamid, A. F.; Belyaeva, A. I.; Bondarenko, V. N.; Davis, J. W.; Galuza, A. A.; Garkusha, I. E.; Haasz, A. A.; Konovalov, V. G.; Kudlenko, A. D.; Poon, M.; Ryzhkov, I. V.; Solodovchenko, S. I.; Shtan, A. F.; Voitsenya, V. S.; Yakimov, K. I.

    The effects of hydrogen ion (H3+) bombardment on the optical properties of polycrystal stainless steel (SS) mirrors were investigated. Ellipsometry, profilometry, scanning electron microscopy, angle distribution of scattered light, and spectral reflectance were used to characterize the surfaces. Results for the bombardment of SS mirrors with ions of fixed energy (0.3, 0.65 and 1.5 keV/H), with ion flux density >(0.5-2) · 1020 H/m2s up to fluences of (1.1-4.3) · 1024 H}/m2 are presented.  The data show that the surface roughness rises with both increasing ion energy and ion fluence, and that surface roughening leads to an increase of the scattered light with a corresponding decrease of reflectance at normal incidence. The thickness of the apparent layer, obtained by ellipsometry, was found to rise with increasing ion energy at fixed ion fluence and with increasing ion fluence at fixed ion energy.  Possible mechanisms for the ion energy effect on the degradation rate of stainless steel mirrors and the origin of the apparent layer are discussed.

  9. Ground-state properties of two-dimensional quantum fluid helium and hydrogen mixtures

    CERN Document Server

    Um, C I; Oh, H G

    1998-01-01

    Using a variational Jastrow wavefunction extended to include a three-body correlation function and a hypernetted chain scheme with the contributions of elementary diagrams, we analyze the ground-state energies and the structural properties of two-dimensional H- sup 4 He and H sub 2 - sup 4 He mixtures. The mixtures are in equilibrium at a lower density compared to a pure sup 4 He system because of the large zero-point energies of the hydrogen atom and molecule. We evaluate the lowering of the ground-state energies as a function of the impurity concentration and total density of mixtures. Comparing the result with boson sup 3 He- sup 4 He mixtures, we show that the shifts of energy mainly come from the difference of the zero-point energies of the impurities rather than from the interatomic potentials.We also analyze the enthalpies to study the miscibility and conclude that boson-boson mixtures are completely phase separated in their equilibria.

  10. Decomposition kinetics study of zirconium hydride by interrupted thermal desorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Mingwang; Liang, Li; Tang, Binghua; Xiang, Wei; Wang, Yuan; Cheng, Yanlin; Tan, Xiaohua, E-mail: caepiee@163.com

    2015-10-05

    Highlights: • Interrupted TDS was applied to investigate the mechanism of ZrH{sub 2} decomposition. • The activation energies for the five desorption peaks were determined. • The origins of the five desorption peaks were identified. • The γZrH phase was observed at ambient conditions. - Abstract: Thermal desorption kinetics of zirconium hydride powder were studied using thermogravimetry and simultaneous thermal desorption spectroscopy. The activation energies for observed desorption peaks were estimated according to Kissinger relation. The intermediate phase composition was studied using X-ray diffraction by rapid cooling on different stages of heating. The origins of the peaks were described as the equilibrium hydrogen pressure of a number of consecutive phase regions that decomposition reaction passed through. The zirconium monohydride γZrH was observed for extended periods of time at ambient conditions, which has been supposed to be metastable for a long time.

  11. Growth, structural, optical, thermal and mechanical properties of cytosinium hydrogen selenite: A novel nonlinear optical single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jaikumar, P. [PG & Research Department of Physics, National College (Autonomous), Tiruchirappalli, 620 001 Tamil Nadu (India); Sathiskumar, S. [Crystal Growth Laboratory, Department of Physics, Periyar EVR College (Autonomous), Tiruchirappalli, 620 023 Tamil Nadu (India); Balakrishnan, T., E-mail: balacrystalgrowth@gmail.com [Crystal Growth Laboratory, Department of Physics, Periyar EVR College (Autonomous), Tiruchirappalli, 620 023 Tamil Nadu (India); Ramamurthi, K. [Crystal Growth & Thin Film laboratory, Department of Physics & Nanotechnology, SRM University, Kattankulathur, 603 203 Kancheepuram, Tamil Nadu (India)

    2016-06-15

    Highlights: • Growth of bulk single crystals of cytosinium hydrogen selenite (CHS) is reported. • Dielectric constant of CHS is measured as a function of Frequency and temperature. • Lower cut off value of UV–vis-NIR spectrum of CHS crystal is observed at 210 nm. • Meyer’s index value of CHS crystal calculated identifies it as a soft material. • Powder SHG efficiency of CHS is about 1.5 times that of KDP crystal. - Abstract: A novel nonlinear optical single crystal of cytosinium hydrogen selenite was grown from aqueous solution of cytosinium hydrogen selenite by slow solvent evaporation method at room temperature. The structural properties of grown crystal have been studied by single crystal and powder X-ray diffraction analysis. Presence of various functional groups was identified from Fourier transform infrared spectroscopy. The optical transmittance and absorbance spectra were recorded by UV–vis-NIR spectrometer and the grown crystal possesses good transparency in the entire visible region. The dielectric constant and dielectric loss of the crystal were calculated as a function of frequency at different temperatures. The mechanical strength of the cytosinium hydrogen selenite crystal was estimated using Vicker’s microhardness tester. Etch patterns of the cytosinium hydrogen selenite crystal were obtained using distilled water as etchant for different etching time. Second harmonic generation efficiency tested using Nd:YAG laser is about 1.5 times that of KDP.

  12. Sensitivity to temperature and material properties of hydrogen concentration at a crack tip in austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Schembri, Philip E [Los Alamos National Laboratory

    2008-01-01

    It is well known that dissolved hydrogen interacts with the stress field at a crack tip, with one result being an intensification of the hydrogen concentration in the region of maximum crack tip stress. The current paper presents recent calculations in ongoing efforts to use coupled stress-diffusion finite element analyses to aid in the structural integrity assessment of pressure vessels containing tritium. The focus of the current work is quantification of the effect of material properties (structural and diffusion) and temperature on the values of maximum stress and hydrogen concentration at the tip of a crack. A one-way-coupled finite element model of a compact tension specimen is used in which the effect of stress and trapping on the hydrogen diffusion is accounted for. Results show that, within the ranges of inputs considered, maximum stress varies approximately linearly with a material's room temperature yield stress but nonlinearly with temperature. Also, peak lattice hydrogen is shown to be a strong function of solubility parameters, a moderate function of yield stress, but only a weak function of trap binding energy and density when trap density is relatively low.

  13. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

    Science.gov (United States)

    Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  14. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Borysow, Jacek, E-mail: jborysow@mtu.edu; Rosso, Leonardo del; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Moraldi, Massimo [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino (Italy)

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  15. Hydrogen-Bond Accepting Properties of New Heteroaromatic Ring Chemical Motifs: A Theoretical Study.

    Science.gov (United States)

    Graton, Jérôme; Le Questel, Jean-Yves; Maxwell, Peter; Popelier, Paul

    2016-02-22

    The prediction of hydrogen-bond (H-bond) acceptor ability is crucial in drug design. This important property is quantified in a large pKBHX database of consistently measured values. We aim to expand the chemical diversity of the studied H-bond acceptors and to increase the range of H-bond strength considered. Two quantum chemical descriptors are contrasted, called ΔE(H) (the change in the energy of a topological hydrogen atom upon complexation) and Vmin (the local minimum in the electrostatic potential on the H-bond accepting site). We performed a systematic analysis of the correlations between pKBHX and Vmin for an initial set of 106 compounds (including O- and N-containing subsets, as well as compounds including sulfur, chlorine, and π-bases). Correlations improve for family dependent subsets, and after outlier treatment, a set of 90 compounds was used to set up a linear equation to predict pKBHX from Vmin. This equation and a previously published equation [Green and Popelier J. Chem. Inf. 2014, 54 (2), 553-561], to predict pKBHX from ΔE(H), were used to predict the pKBHX values for 22 potentially biologically active heteroaromatic ring compounds, [Pitt et al. J. Med. Chem. 2009, 52 (9), 2952-2963], among which several structures still remain experimentally unavailable. H-Bond basicity of sp(2) nitrogen sites were consistently predicted with both descriptors. A worse agreement was found with carbonyl acceptor sites, with the stronger deviations observed for the lactam groups. It was shown that secondary interactions involving the neighboring NH group were influencing the results. Substitution of the NH group with an NMe group resulted in an improved consistency from both Vmin and ΔE(H) predictions, the latter being more prominently affected by the methyl substitution. Both approaches appear as efficient procedures for the H-bond ability prediction of novel heteroaromatic rings. Nevertheless, the ΔE(H) parameter presents slight chemical structure limitations

  16. Computer simulation of hydrogen permeability of structural materials through protective coating defect

    Science.gov (United States)

    Kostikova, E. K.; Zaika, Yu V.

    2015-12-01

    In the context of problems of hydrogen and thermonuclear power engineering intensive research of the hydrogen isotopes properties is being conducted. Mathematical models help to specify physical-chemical ideas about the interaction of hydrogen isotopes with structural materials, to estimate the limiting factors and to significantly reduce the expenses of experimental research by means of numerical simulation for different parameters and experimental conditions (including extreme ones). Classical diffusion models are often insufficient. The paper is devoted to the models and numerical solution of the boundary-value problems of hydrogen permeability taking into account nonlinear sorption-desorption dynamics on the surface. Algorithms based on difference approximations. The results of computer simulation of the hydrogen flux from a structural material sample are presented.

  17. Distinctive properties of high hydrogen producing extreme thermophiles, Caldicellulosiruptor saccharolyticus and Thermotaga elfii

    NARCIS (Netherlands)

    Niel, van E.W.J.; Budde, M.A.W.; Haas, de G.G.; Wal, van der F.J.; Claassen, P.A.M.; Stams, A.J.M.

    2002-01-01

    Growth and hydrogen production by two extreme thermophiles during sugar fermentation was investigated. In cultures of Caldicellulosiruptor saccharolyticus grown on sucrose and Thermotoga elfii grown on glucose stoichiometries of 3.3 mol of hydrogen and 2 mol of acetate per mol C6-sugar unit were

  18. Studies on the properties of an epithermal-neutron hydrogen analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Papp, A., E-mail: papppa@atomki.h [Institute of Nuclear Research of the Hungarian Academy of Sciences, Pf. 51, 4001 Debrecen (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences, Pf. 51, 4001 Debrecen (Hungary); Institute of Experimental Physics, University of Debrecen, Pf. 105, 4010 Debrecen-10 (Hungary)

    2010-09-15

    Systematic investigations have proved the advantages of the Epithermal Neutron Analyzer (ETNA) for bulk hydrogen analysis as compared to the thermal neutron techniques. Results can contribute, for example, to the design and construction of instruments needed for the detection and identification of plastic anti-personnel landmines, explosives hidden in airline baggage and cargo containers via hydrogen contents as an indicator of their presence.

  19. Ignition properties of methane/hydrogen mixtures in a rapid compression machine

    NARCIS (Netherlands)

    Gersen, S.; Anikin, N. B.; Mokhov, A. V.; Levinsky, H. B.

    We investigate changes in the combustion behavior of methane, the primary component of natural gas, upon hydrogen addition by characterizing the autoignition behavior of methane/hydrogen mixtures in a rapid compression machine (RCM). Ignition delay times were measured under stoichiometric conditions

  20. The impact of carbon materials on the hydrogen storage properties of light metal hydrides

    NARCIS (Netherlands)

    Adelhelm, P.A.|info:eu-repo/dai/nl/313907854; de Jongh, P.E.|info:eu-repo/dai/nl/186125372

    2011-01-01

    The safe and efficient storage of hydrogen is still one of the remaining challenges towards fuel cell powered cars. Metal hydrides are a promising class of materials as they allow the storage of large amounts of hydrogen in a small volume at room temperature and low pressures. However, usually the

  1. The ground state properties of spin-aligned atomic hydrogen, deuterium, and tritium

    Science.gov (United States)

    Etters, R. D.; Dugan, J. V., Jr.; Palmer, R. W.

    1975-01-01

    The internal energy, pressure, and compressibility of ground-state, spin-aligned atomic hydrogen, deuterium, and tritium are calculated assuming that all pair interactions occur via the atomic triplet (spin-aligned) potential. The conditions required to obtain atomic hydrogen and its isotopes in bulk are discussed; such a development would be of value in propulsion systems because of the light mass and energetic recombination of atomic hydrogen. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K, and that tritium forms a liquid with a binding energy of approximately -0.75 K per atom at a molar volume of 130 cu cm per mole. The pair distribution function for these systems is calculated, and the predicted superfluid behavior of atomic triplet hydrogen and tritium is briefly discussed.

  2. Effect of hydrogen peroxide and sodium perborate on biomechanical properties of human dentin.

    Science.gov (United States)

    Chng, Hui Kheng; Palamara, Joseph E A; Messer, Harold H

    2002-02-01

    This study compared the ultimate tensile strength, micropunch shear strength, and microhardness of bleached and unbleached human dentin. Forty-four intact premolars were root canal treated and randomly divided into four groups. Bleaching agents were sealed in pulp chambers, as in clinical use. Group 1 (control) was treated with water, group 2 with 30% hydrogen peroxide, group 3 with sodium perborate mixed with water, and group 4 with sodium perborate mixed with 30% hydrogen peroxide. The teeth were stored in saline at 37 degrees C for 7 days. The teeth were then sectioned and biomechanical tests were carried out on dentin specimens that were obtained from all teeth. Intracoronal bleaching with 30% hydrogen peroxide and sodium perborate used either alone or in combination weakened dentin. Hydrogen peroxide alone tended to be more damaging than sodium perborate used alone or sodium perborate mixed with hydrogen peroxide.

  3. Dependence of the tensile properties of 316 L parent material and welds on implanted hydrogen and/or helium

    Science.gov (United States)

    Schroeder, Herbert; Liu, Wanpei

    1992-09-01

    The interest in the low temperature tensile properties of candidate alloys for first wall and blanket structures of future fusion devices is due to the possible low pressure water cooling and the associated low operation temperature in recent design studies. Therefore, the tensile properties of hydrogen and/or helium implanted 316 L stainless steel and its weldments as a function of gas concentrations and temperature were investigated. The main effects of the implantation are hardening, resulting in large increases of the yield strength proportional to the implanted gas concentration, and a gradual decrease of the corresponding rupture strain. The ultimate tensile stresses are less affected. The effect of helium implantation seems to be more pronounced than that of hydrogen implantation. At 673 K most of the implantation induced changes are recovered. Generally parent material and welds still show large ductility (≥20%) under all conditions investigated.

  4. An ab initio study of the properties of some lithium-bonded complexes - Comparison with their hydrogen-bonded analogues

    Science.gov (United States)

    Ford, Thomas A.

    2013-07-01

    Ab initio calculations have been carried out on a series of complexes formed between lithium fluoride, chloride and bromide on the one hand, and ammonia, water, phosphine and hydrogen sulfide on the other. The calculations were performed using the Gaussian-09 program, at the second order level of Møller-Plesset perturbation theory and with Dunning's augmented correlation-consistent polarized valence triple-zeta basis set. The properties studied were the molecular structures, interaction energies and vibrational spectra. The results have been compared with those for an analogous set of complexes formed between the three acids hydrogen fluoride, chloride and bromide, and the same four Lewis bases. Common features between the properties of both sets of complexes have been highlighted, and the differences rationalized.

  5. Study of the mechanisms of heavy-ion induced desorption on accelerator-relevant materials; Untersuchung der Mechanismen schwerioneninduzierter Desorption an beschleunigerrelevanten Materialien

    Energy Technology Data Exchange (ETDEWEB)

    Bender, Markus

    2008-02-22

    The ion beam loss induced desorption is a performance limitation for low charge state heavy ion accelerators. If charge exchanged projectile ions get lost onto the beam pipe, desorption of gas is stimulated resulting in a pressure increase inside of the synchrotron and thus, a dramatically reduction of the beam life time. To minimize the amount of desorbed gas an experimental program has been started to measure the desorption yields (released gas molecules per incident ion) of various materials and different projectile ions. The present work is a contribution to the understanding of the physical processes behind the ion beam loss induced desorption. The yield measurements by the pressure rise method have been combined for the rst time with in situ ion beam analysis technologies such as ERDA and RBS. With this unique method the desorption behavior of a sample can be correlated to its surface and bulk properties. The performed experiments with 1,4 MeV/u Xenon-Ions show that the ion induced desorption is mainly a surface effect. Sputtered oxide layers or impurities do not contribute to the desorbed gas significantly. Nevertheless bulk properties play an important role in the desorption strength. Pure metallic samples desorb less gas than isolating materials under swift heavy ion irradiation. From the experimental results it was possible to estimate the desorption yields of various materials under ion bombardment by means of an extended inelastic thermal-spike-model. The extension is the combination of the thermal-spike's temperature map with thermal desorption. Within this model the ion induced desorption can be regarded as the release of adsorbates from a transient overheated spot on the samples surface around the ion impact. Finally a copper substrate with a gold coated surface was developed and proposed as a suitable material for a beam loss collimator with minimum desorption to ensure the performance of GSI's SIS18 in high current beam operation. (orig.)

  6. Quantitative evaluation on activated property-tunable bulk liquid water with reduced hydrogen bonds using deconvoluted Raman spectroscopy.

    Science.gov (United States)

    Chen, Hsiao-Chien; Mai, Fu-Der; Yang, Kuang-Hsuan; Chen, Liang-Yih; Yang, Chih-Ping; Liu, Yu-Chuan

    2015-01-06

    Interesting properties of water with distinguishable hydrogen-bonding structure on interfacial phase or in confined environment have drawn wide attentions. However, these unique properties of water are only found within the interfacial phase and confined environment, thus, their applications are limited. In addition, quantitative evaluation on these unique properties associating with the enhancement of water's physical and chemical activities represents a notable challenge. Here we report a practicable production of free-standing liquid water at room temperature with weak hydrogen-bonded structure naming Au nanoparticles (NPs)-treated (AuNT) water via treating by plasmon-induced hot electron transfer occurred on resonantly illuminated gold NPs (AuNPs). Compared to well-known untreated bulk water (deionized water), the prepared AuNT water exhibits many distinct activities in generally physical and chemical reactions, such as high solubilities to NaCl and O2. Also, reducing interaction energy within water molecules provides lower overpotential and higher efficiency in electrolytic hydrogen production. In addition, these enhanced catalytic activities of AuNT water are tunable by mixing with deionized water. Also, most of these tunable activities are linearly proportional to its degree of nonhydrogen-bonded structure (DNHBS), which is derived from the O-H stretching in deconvoluted Raman spectrum.

  7. Effect of Li Termination on the Electronic and Hydrogen Storage Properties of Linear Carbon Chains: A TAO-DFT Study.

    Science.gov (United States)

    Seenithurai, Sonai; Chai, Jeng-Da

    2017-07-10

    Accurate prediction of the electronic and hydrogen storage properties of linear carbon chains (C n ) and Li-terminated linear carbon chains (Li2C n ), with n carbon atoms (n = 5-10), has been very challenging for traditional electronic structure methods, due to the presence of strong static correlation effects. To meet the challenge, we study these properties using our newly developed thermally-assisted-occupation density functional theory (TAO-DFT), a very efficient electronic structure method for the study of large systems with strong static correlation effects. Owing to the alteration of the reactivity of C n and Li2C n with n, odd-even oscillations in their electronic properties are found. In contrast to C n , the binding energies of H2 molecules on Li2C n are in (or close to) the ideal binding energy range (about 20 to 40 kJ/mol per H2). In addition, the H2 gravimetric storage capacities of Li2C n are in the range of 10.7 to 17.9 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li2C n can be high-capacity hydrogen storage materials that can uptake and release hydrogen at temperatures well above the easily achieved temperature of liquid nitrogen.

  8. Structural and optical properties of amorphous hydrogenated silicon carbonitride films produced by PECVD

    Science.gov (United States)

    Vassallo, E.; Cremona, A.; Ghezzi, F.; Dellera, F.; Laguardia, L.; Ambrosone, G.; Coscia, U.

    2006-09-01

    Amorphous hydrogenated silicon carbonitride thin films (a-Si:C:N:H), deposited by plasma enhanced chemical vapour deposition (PECVD) using hexamethyldisilazane (HMDSN) as monomer and Ar as feed gas, have been investigated for their structural and optical properties as a function of the deposition RF plasma power, in the range of 100-300 W. The films have been analysed by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), UV-vis-NIR spectrophotometry and atomic force microscopy (AFM). From the analysis of the FT-IR spectra it results that the films become more amorphous and inorganic as RF plasma power increases. The incorporation of oxygen in the deposited layers, mainly due to the atmospheric attack, has been evaluated by XPS and FT-IR spectroscopy. Reflectance/transmittance spectra, acquired in the range of 200-2500 nm, allow to descrive the film absorption edge for interband transitions. A relationship between the optical energy band gap, deduced from the absorption coefficient curve, and the deposition RF plasma power has been investigated. The reduction of the optical energy gap from 3.85 to 3.69 eV and the broadening of the optical absorption tail with RF plasma power increasing from 100 to 300 W are ascribed to the growth of structural disorder, while the increase of the refractive index, evaluated at 630 nm, is attributed to a slight densification of the film. The AFM analysis confirms the amorphous character of the films and shows how the deposited layers become rougher when RF plasma power increases. The wettability of the film has been studied and related to the chemical composition and to the morphology of the deposited layers.

  9. Structural and optical properties of amorphous hydrogenated silicon carbonitride films produced by PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Vassallo, E. [Istituto di Fisica del Plasma, CNR, Milan (Italy)]. E-mail: vassallo@ifp.cnr.it; Cremona, A. [Istituto di Fisica del Plasma, CNR, Milan (Italy); Ghezzi, F. [Istituto di Fisica del Plasma, CNR, Milan (Italy); Dellera, F. [Istituto di Fisica del Plasma, CNR, Milan (Italy); Laguardia, L. [Istituto di Fisica del Plasma, CNR, Milan (Italy); Ambrosone, G. [INFM-Universita di Napoli Federico II, Dip. di Scienze Fisiche, Naples (Italy); Coscia, U. [INFM-Universita di Napoli Federico II, Dip. di Scienze Fisiche, Naples (Italy)

    2006-09-15

    Amorphous hydrogenated silicon carbonitride thin films (a-Si:C:N:H), deposited by plasma enhanced chemical vapour deposition (PECVD) using hexamethyldisilazane (HMDSN) as monomer and Ar as feed gas, have been investigated for their structural and optical properties as a function of the deposition RF plasma power, in the range of 100-300 W. The films have been analysed by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), UV-vis-NIR spectrophotometry and atomic force microscopy (AFM). From the analysis of the FT-IR spectra it results that the films become more amorphous and inorganic as RF plasma power increases. The incorporation of oxygen in the deposited layers, mainly due to the atmospheric attack, has been evaluated by XPS and FT-IR spectroscopy. Reflectance/transmittance spectra, acquired in the range of 200-2500 nm, allow to descrive the film absorption edge for interband transitions. A relationship between the optical energy band gap, deduced from the absorption coefficient curve, and the deposition RF plasma power has been investigated. The reduction of the optical energy gap from 3.85 to 3.69 eV and the broadening of the optical absorption tail with RF plasma power increasing from 100 to 300 W are ascribed to the growth of structural disorder, while the increase of the refractive index, evaluated at 630 nm, is attributed to a slight densification of the film. The AFM analysis confirms the amorphous character of the films and shows how the deposited layers become rougher when RF plasma power increases. The wettability of the film has been studied and related to the chemical composition and to the morphology of the deposited layers.

  10. Effect of hydrogen on the microstructure and electrochemical properties of Si nanoparticles synthesized by microwave plasma

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Jeongboon; Lee, Jeongeun; Kim, Joonsoo; Jang, Boyun, E-mail: byjang@kier.re.kr

    2016-09-01

    We synthesized silicon (Si) nanoparticles using an atmospheric microwave plasma process, and investigated the effects of hydrogen (H{sub 2}) injection on their microstructure during the synthesis. Two nozzles were applied to inject H{sub 2} (swirling and rectilinear H{sub 2}). Our microstructural analysis indicated that the amount and method of H{sub 2} injection were critical for completion of the reaction from silicon tetrachloride (SiCl{sub 4}) to Si, as well as to obtain highly crystalline Si nanoparticles. The swirling H{sub 2} was especially critical due to its formation of vortex flow, which allowed relatively long residence time of the H-ions in plasma. The Si nanoparticles synthesized by the atmospheric plasma process had core-shell structures that consisted of crystalline Si cores with amorphous SiO{sub x} shells of 5–15 nm thickness. We also investigated the feasibility of the synthesized Si nanoparticles as anode materials in a lithium-ion battery (LIB). For the core-shell structured Si nanoparticles, we obtained the first reversible capacity of 1204 mAhg{sup −1}, and a capacity retention of 82.2% at the 50{sup th} cycle. - Highlights: • We synthesized Si nanoparticles by an atmospheric microwave plasma process. • We investigated the effects of injected H{sub 2} on the microstructures of Si nanoparticles. • Swirling H{sub 2} was critical, due to the formation of vortex flow in plasma. • The synthesized Si nanoparticles had core (crystalline Si)-shell (SiO{sub x}) structures. • The electrochemical properties depend on its core-shell structures as LIB anode.

  11. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  12. Adsorption and Reactive Desorption on Metal-Organic Frameworks: A Direct Strategy for Lactic Acid Recovery.

    Science.gov (United States)

    Stassin, Timothée; Reinsch, Helge; Van de Voorde, Ben; Wuttke, Stefan; Medina, Dana D; Stock, Norbert; Bein, Thomas; Ameloot, Rob; De Vos, Dirk

    2017-02-08

    Biomass-derived lactic acid (LA) is an important platform chemical towards the sustainable production of numerous materials. However, the fermentation process currently in use is limited by the difficult recovery of the LA product from the fermentation broth and results in the generation of stoichiometric amounts of gypsum waste. Herein, we show that metal-organic frameworks (MOFs) of the UiO-66(Zr) type are effective adsorbents for the separation of LA from aqueous (buffer) solutions. These frameworks based on zirconium clusters and terephthalic acid derivatives display a tremendous uptake (up to 42 wt %) and a high affinity for LA. The latter can further be tuned by changing the hydrogen-bonding properties of the functional groups present on the organic ligand. A Rietveld refinement disclosed the specific interaction of LA with the clusters of UiO-66(Zr) and a preferential adsorption on open zirconium sites. Taking advantage of the catalytic activity of UiO-66(Zr), desorption of LA was performed in alcohols to recover up to 73 % as ester. Applied to the recovery of LA, adsorption and reactive desorption offer a direct and gypsum-free strategy as an alternative for the current multi-step process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Changes in Storage Properties of Hydrides Induced by Ion Irradiation

    Directory of Open Access Journals (Sweden)

    Jasmina GRBOVIĆ NOVAKOVIĆ

    2013-05-01

    Full Text Available The influence of structural changes caused by irradiation with different ions, their energies and fluences on sorption properties has been investigated. Results suggest that there are several mechanisms of desorption depending on defect concentration, their interaction and ordering. It has been also demonstrated that the changes in near-surface area play the crucial role in hydrogen desorption kinetics. It is confirmed that there is possibility to control the thermodynamic parameters of these systems by controlling vacancies depth profile and concentration. DOI: http://dx.doi.org/10.5755/j01.ms.19.2.1579

  14. Time dependence of silica optical properties during the implantation of fast hydrogen ions: Theory

    CERN Document Server

    Barannik, E; Zhurenko, V; Kononenko, S; Kononenko, O

    2015-01-01

    Formation, excitation and passivation of defects by absorbed hydrogen have been extensively reported in the literature. Here we present a basic luminescence-diffusion model to simulate creation and chemical annealing behavior of non-bridging oxygen hole centers in silica by their treatment under a long-time hydrogen implantation. The model is in a good agreement with experimental data and explains the uncommon nonmonotonic time dependence of the non-bridging oxygen hole centers luminescence during the hydrogen implantation. The proposed model establishes the quantitative relation between the intensity dependence of luminescence on its intrinsic diffusivity, hydrogen concentration, defect concentration and cross-section of their creation. Possibilities to estimate these parameters based on the experimental data for the efficiency of silica luminescence are also discussed.

  15. A composite of complex and chemical hydrides yields the first Al-based amidoborane with improved hydrogen storage properties.

    Science.gov (United States)

    Dovgaliuk, Iurii; Jepsen, Lars H; Safin, Damir A; Łodziana, Zbigniew; Dyadkin, Vadim; Jensen, Torben R; Devillers, Michel; Filinchuk, Yaroslav

    2015-10-05

    The first Al-based amidoborane Na[Al(NH2 BH3 )4 ] was obtained through a mechanochemical treatment of the NaAlH4 -4 AB (AB=NH3 BH3 ) composite releasing 4.5 wt % of pure hydrogen. The same amidoborane was also produced upon heating the composite at 70 °C. The crystal structure of Na[Al(NH2 BH3 )4 ], elucidated from synchrotron X-ray powder diffraction and confirmed by DFT calculations, contains the previously unknown tetrahedral ion [Al(NH2 BH3 )4 ](-) , with every NH2 BH3 (-) ligand coordinated to aluminum through nitrogen atoms. Combination of complex and chemical hydrides in the same compound was possible due to both the lower stability of the AlH bonds compared to the BH ones in borohydride, and due to the strong Lewis acidity of Al(3+) . According to the thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS) studies, Na[Al(NH2 BH3 )4 ] releases in two steps 9 wt % of pure hydrogen. As a result of this decomposition, which was also supported by volumetric studies, the formation of NaBH4 and amorphous product(s) of the surmised composition AlN4 B3 H(0-3.6) were observed. Furthermore, volumetric experiments have also shown that the final residue can reversibly absorb about 27 % of the released hydrogen at 250 °C and p(H2 )=150 bar. Hydrogen re-absorption does not regenerate neither Na[Al(NH2 BH3 )4 ] nor starting materials, NaAlH4 and AB, but rather occurs within amorphous product(s). Detailed studies of the latter one(s) can open an avenue for a new family of reversible hydrogen storage materials. Finally, the NaAlH4 -4 AB composite might become a starting point towards a new series of aluminum-based tetraamidoboranes with improved hydrogen storage properties such as hydrogen storage density, hydrogen purity, and reversibility. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Phase structure and hydrogen absorption property of LaMg{sub 2}Cu

    Energy Technology Data Exchange (ETDEWEB)

    Hu Lin [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Han Shumin, E-mail: hanshm@ysu.edu.c [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Li Jinhua [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Yang Cheng; Li Yuan [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Mingzhi [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2010-02-15

    LaMg{sub 2}Cu alloy was prepared by inductive melting and then was annealed at 723 K for 10 h in 0.1 MPa argon atmospheres. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the alloy consisted of LaMg{sub 2}Cu{sub 2} phase, LaMg{sub 3} phase and a few of unknown phases. The annealing treatment improved the equilibrium pressure and hydrogen absorption capacity of LaMg{sub 2}Cu alloy. The hydrogen absorption capacity of the as-cast and annealed alloys at 473 K were 2.86 and 3.33 wt.%, and the equilibrium pressure were 1 and 3 MPa, respectively. The enthalpy and entropy of LaMg{sub 2}Cu-H hydriding reaction were determined. LaMg{sub 2}Cu alloy could absorb hydrogen with rapid hydriding kinetics, the hydrogen absorption rate of LaMg{sub 2}Cu increased from 423 K to 498 K and the uptake time for hydrogen content to reach 90% of the maximum storage capacity for annealed alloy was less than 550 s at 498 K. The experimental curves of hydrogen absorption kinetics could be fitted with good accuracy by Jander equation. It suggested that the hydriding of LaMg{sub 2}Cu alloy was a three-dimensional diffusion-controlled process. And the activation energy and pre-exponential factor of LaMg{sub 2}Cu alloy were also calculated.

  17. Effect of Titanium Doping of Al(111) Surfaces on Alane Formation Mobility, and Desorption

    Energy Technology Data Exchange (ETDEWEB)

    Chopra I. S.; Graetz J.; Chaudhuri, S.; Veyan, J.-F.; Chabal, Y. J.

    2011-07-05

    Alanes are critical intermediates in hydrogen storage reactions for mass transport during the formation of complex metal hydrides. Titanium has been shown to promote hydrogen desorption and hydrogenation, but its role as a catalyst is not clear. Combining surface infrared (IR) spectroscopy and density functional theory (DFT), the role of Ti is explored during the interaction of atomic hydrogen with Ti-doped Al(111) surfaces. Titanium is found to reduce the formation of large alanes, due to a decrease of hydrogen mobility and to trapping of small alanes on Ti sites, thus hindering oligomerization. For high doping levels ({approx}0.27 ML Ti) on Al(111), only chemisorbed AlH{sub 3} is observed on Ti sites, with no evidence for large alanes. Titanium also dramatically lowers the desorption temperature of large alanes from 290 to 190 K, due to a more restricted translational motion of these alanes.

  18. Hydrogen Fuel Cells and Storage Technology: Fundamental Research for Optimization of Hydrogen Storage and Utilization

    Energy Technology Data Exchange (ETDEWEB)

    Perret, Bob; Heske, Clemens; Nadavalath, Balakrishnan; Cornelius, Andrew; Hatchett, David; Bae, Chusung; Pang, Tao; Kim, Eunja; Hemmers, Oliver

    2011-03-28

    Design and development of improved low-cost hydrogen fuel cell catalytic materials and high-capacity hydrogenn storage media are paramount to enabling the hydrogen economy. Presently, effective and durable catalysts are mostly precious metals in pure or alloyed form and their high cost inhibits fuel cell applications. Similarly, materials that meet on-board hydrogen storage targets within total mass and volumetric constraints are yet to be found. Both hydrogen storage performance and cost-effective fuel cell designs are intimately linked to the electronic structure, morphology and cost of the chosen materials. The FCAST Project combined theoretical and experimental studies of electronic structure, chemical bonding, and hydrogen adsorption/desorption characteristics of a number of different nanomaterials and metal clusters to develop better fundamental understanding of hydrogen storage in solid state matrices. Additional experimental studies quantified the hydrogen storage properties of synthesized polyaniline(PANI)/Pd composites. Such conducting polymers are especially interesting because of their high intrinsic electron density and the ability to dope the materials with protons, anions, and metal species. Earlier work produced contradictory results: one study reported 7% to 8% hydrogen uptake while a second study reported zero hydrogen uptake. Cost and durability of fuel cell systems are crucial factors in their affordability. Limits on operating temperature, loss of catalytic reactivity and degradation of proton exchange membranes are factors that affect system durability and contribute to operational costs. More cost effective fuel cell components were sought through studies of the physical and chemical nature of catalyst performance, characterization of oxidation and reduction processes on system surfaces. Additional development effort resulted in a new hydrocarbon-based high-performance sulfonated proton exchange membrane (PEM) that can be manufactured at low

  19. Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    J. Bornacelli

    2014-01-01

    Full Text Available Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs have become the main building block of silicon photonic (modulators, waveguide, source, and detectors. In this work, we present an approach based on implantation of Ag (or Au ions and a proper thermal annealing in order to improve the photoluminescence (PL emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 μm under surface. Once Si-NCs are formed inside the SiO2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs.

  20. Recent progress on the hydrogen storage properties of ZrCo-based alloys applied in International Thermonuclear Experimental Reactor (ITER

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2017-02-01

    Full Text Available Under the development of International Thermonuclear Experimental Reactor (ITER system aimed at realizing the controllable fusion reaction to solve the energy crisis fundamentally, there is an urgent need to find an appropriate material for tritium handling. ZrCo alloy is considered to be a promising candidate for the storage and delivery of hydrogen isotopes due to the favorable characteristics such as low plateau pressure for absorption, high dissociation pressure at moderate temperature and better ability of trapping 3He. However, the hydrogen induced disproportionation and the slower recovery/deliverty rate of ZrCo-based alloys have limited their further application in ITER system. This review summarizes the efforts towards enhancing the hydrogen storage properties of ZrCo-based alloys including element substitution, surface modification, disproportionation mechanism investigation and the isotope effect study. Element substitution and surface modification play positive role to improve the anti-disproportionation ability and kinetic property of the alloys. However, the ZrCo-based alloys require to be further modified by more attempts such as new composition, novelty modification method or catalyst addition in order to better satisfy the application demands for tritium handling. Moreover, new insight for further understanding the inner disproportionation mechanisms of this material is needed by combining the advance characterization and theoretical analysis, which is in favor of addressing the disproportionation problem of the ZrCo-based alloys essentially.

  1. The intriguing electronic and optical properties modulation of hydrogen and fluorine codecorated silicene layers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qun; Tan, Chunjian [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Opto-Electronic Engineering, Chongqing University, 400044 Chongqing (China); Meng, Ruishen; Jiang, Junke; Liang, Qiuhua; Sun, Xiang [Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Opto-Electronic Engineering, Chongqing University, 400044 Chongqing (China); Yang, Daoguo [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Chen, Xianping, E-mail: xianpingchen@cqu.edu.cn [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Opto-Electronic Engineering, Chongqing University, 400044 Chongqing (China)

    2017-03-15

    Highlights: • The HSiF bilayer is very stable due to the high binding energy even larger than the ones of bilayer graphene. • The HSiF bilayer exhibits a moderate direct band gap of 0.296 eV much lower than that of HSiF monolayer. • All the HSiF layers have a direct band gap nature, irrespective of stacking pattern, thickness and external electric fields, which is an advantage over MoS{sub 2} layers. Besides, it is advantageous to the application of HSiF layers in the field of optical devices. • The external electric field can effectively tune the band gaps of HSiF layers. Especially, even a semiconductor–metal transition occurs. • After the formation of HSiF bilayer, the complete electron-hole separation enhances the photocatalytic efficiency of HSiF bilayer and it exhibits a significantly improved visible light adsorption peak. - Abstract: First-principles calculations based on density-functional theory reveal some superior physical properties of hydrogen and fluorine co-decorated silicene (HSiF) monolayer and bilayer. Our simulated results reveal that the HSiF monolayer is a large direct band gap semiconductor greatly differing from the gapless semi-metallic silicene. There exists strong interlayer coupling in HSiF bilayer, leading to the good stabilities of HSiF bilayer even beyond bilayer graphene. The proposed HSiF bilayer exhibits a moderate direct band gap of 0.296 eV which is much lower than that of HSiF monolayer. Encouragingly, HSiF layers all have a direct band gap nature, irrespective of stacking pattern, thickness and external electric fields, which is an advantage over MoS{sub 2} layers. Furthermore, an out-of-plane electric field has an evident impact on the band structures of the HSiF monolayer and bilayer. Especially, the band gap of HSiF bilayer can be effectively tuned by external electric field, even a semiconductor–metal transition occurs. More importantly, the HSiF bilayer exhibits a significant improved visible light adsorption

  2. Study of the hydrogen behavior in amorphous hydrogenated materials of type a - C:H and a - SiC:H facing fusion reactor plasma; Etude du comportament de l`hydrogene dans des materiaux amorphes hydrogenes de type a - C:H et a - SiC:H devant faire face au plasma des reacteurs a fusion

    Energy Technology Data Exchange (ETDEWEB)

    Barbier, G. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire

    1997-04-10

    Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. First, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce these interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a - SiC:H substrate can be beneficial in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a-SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a - C:H and a - SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modelling of hydrogen diffusion under irradiation has been also proposed. (author) 176 refs.

  3. The effect of TTNT nanotubes on hydrogen sorption using MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Brum, Mariana Coutinho; Jardim, Paula Mendes; Conceicao, Monique Osorio Talarico da; Santos, Dilson Silva dos, E-mail: monique@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

    2013-11-01

    Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH{sub 2} with the addition of TTNT (TiTanate nanotubes). The MgH{sub 2} -TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (%)) on the hydrogen capacity was evaluated. The milling of pure MgH{sub 2} was performed for 24 hours and afterwards the MgH{sub 2} -TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to evaluate the nanotube synthesis and show the particle morphology of the MgH{sub 2} -TTNT composite, respectively. The Differential Scanning Calorimetry (DSC) examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%). (author)

  4. The effect of TTNT nanotubes on hydrogen sorption using MgH2

    Directory of Open Access Journals (Sweden)

    Mariana Coutinho Brum

    2013-06-01

    Full Text Available Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH2 with the addition of TTNT (TiTanate NanoTubes. The MgH2-TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (% on the hydrogen capacity was evaluated. The milling of pure MgH2 was performed for 24 hours and afterwards the MgH2-TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM and Scanning Electron Microscopy (SEM were used to evaluate the nanotube synthesis and show the particle morphology of the MgH2-TTNT composite, respectively. The Differential Scanning Calorimetry (DSC examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%.

  5. The Effects of composts on adsorption-desorption of three ...

    African Journals Online (AJOL)

    Michael Horsfall

    (1/n des). @JASEM. Pesticides adsorption and desorption are the key processes determining whether pesticide used will have any impact on environmental quality. For most of the pesticides soil organic matter and clay contents are the most important properties which affect the sorption and transformation (Durovic et al., ...

  6. Fundamental study that produce hydrogen with solar enregy. ; Property with simulated power source. Taiyo energy ni yoru suiso seizo ni kansuru kiso kenkyu. ; Mogi dengen ni yoru tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Ota, H.; Aoki, Y.; Tani, T. (Science University of Tokyo, Tokyo (Japan). Faculty of Engineering)

    1990-12-06

    Mankind is currently confronted by several environmental problems. Among these problems are depletion of fossil fuel reseves, and global warming caused by CO {sub 2} and the consequent environmental damage. These problems demand the most serious consideration and solution. Fuel cell systems are one of the prospective energy systems. Fuel cell systems produce electricity electrochemically, and they produce it most efficiently, and with almost a complete absence of emissions. This basic study concerns the production of hydrogen. Hydrogen is the fuel used by fuel cells. Hydrogen is produced by the electrolysis of water with solar energy. In this paper, as a first step, the hydrogen generator {prime} s properties are measured. These properties are measured by supplying electricity both continuously and intermittently from a DC power source which simulates photovoltaic modules. Our conclusion is that, in the near future, utilization of a hydrogen generator may be feasible if electricity is supplied from photovoltaic modules. 3 refs., 12 figs., 2 tabs.

  7. SPS Ion Induced Desorption Experiment

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    This experiment will give a study about the induced desorption from heavy ion (Indium ion run from week 45 in SPS T4-H8 area) impacting LHC type graphite collimator. 4 different samples are located in the 4 chambers 90° one to each other: pure graphite, graphite with copper coating, graphite with NEG coating, 316LN stainless steal (reference).

  8. Hydrogen storage in metal-organic frameworks: An investigation of structure-property relationships

    Science.gov (United States)

    Rowsell, Jesse

    Metal-organic frameworks (MOFs) have been identified as candidate hydrogen storage materials due to their ability to physisorb large quantities of small molecules. Thirteen compounds (IRMOF-1, -2, -3, -6, -8, -9, -11, -13, -18, -20, MOF-74, MOF-177 and HKUST-1) have been prepared and fully characterized for the evaluation of their dihydrogen (H2) adsorption properties. All compounds display approximately type I isotherms with no hysteresis at 77 K up to 1 atm. The amount adsorbed ranges from 0.89 to 2.54 wt%; however, saturation is not achieved under these conditions. The influences of link functionalization, catenation and topology are examined for the eleven MOFs composed of Zn4O(O2C-)6 clusters. Enhanced H2 uptake by catenated compounds is rationalized by increased overlap of the surface potentials within their narrower pores. This is corroborated by the larger isosteric heat of adsorption of IRMOF-11 compared to IRMOF-1. Inelastic neutron scattering spectroscopic analysis of four Zn4O-based materials (IRMOF-1, -8, -11, and MOF-74) under a range of H2 loading suggests the presence of multiple localized adsorption sites on both the inorganic and organic moieties. To determine the structural details of the adsorption sites, variable temperature single crystal X-ray diffraction was used to analyze adsorbed argon and dinitrogen molecules in IRMOF-1. The principle binding site was found to be the same for both adsorbates and is located on faces of the octahedral Zn4O(O2C-)6 clusters with close contacts to three carboxylate groups. A total of eight symmetry-independent adsorption sites were identified for argon at 30 K. Similar sites were observed for dinitrogen, suggesting that they are good model adsorbates for the behaviour of dihydrogen. Two additional materials composed of inorganic clusters with coordinatively unsaturated metal sites (MOF-74, HKUST-1) were examined and their increased capacities and isosteric heats of adsorption provide further evidence that the

  9. Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing

    Directory of Open Access Journals (Sweden)

    Shiliu Yin

    2016-06-01

    Full Text Available Understanding how the defects interact with each other and affect the properties of ZnO:Al films is very important for improving their performance as a transparent conductive oxide (TCO. In the present work, we studied the effects of hydrogen annealing on the structural, optical and electrical properties of ZnO:Al films prepared by magnetron sputtering. High resolution transmission electron microscopy observations reveal that annealing at ∼300 oC induces the formation of partial dislocations (PD and stacking faults (SF, which disrupt the lattice periodicity leading to decreased grain size. Annealing at temperatures above ∼500 oC can remove the PD and SF, but large number of zinc vacancies will be generated. Our results show that when films are annealed at ∼500 oC, the oxygen-related defects (interstitials Oi, etc. in the as-grown films can be remarkably removed or converted, which lead to increments in the carrier concentration, mobility, and the transmittance in the visible range. At annealing temperatures above 550 oC, the hydrogen etching effect becomes predominant, and Al donors are deactivated by zinc vacancies. We also find an abnormal endothermic process by thermal analysis and an abnormal increase in the resistivity during heating the sample under hydrogen atmosphere, based on which the interaction of Oi with the defects (mainly Al donors and PD is discussed. It is also demonstrated that by annealing the as-grown AZO films at ∼500 oC under hydrogen atmosphere, high performance TCO films with a low resistivity of 4.48 × 10−4 Ωcm and high transmittance of above 90% in the visible light are obtained.

  10. Influences of defects evolvement on the properties of sputtering deposited ZnO:Al films upon hydrogen annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Shiliu; Shirolkar, Mandar M.; Li, Jieni; Li, Ming; Song, Xiao; Dong, Xiaolei; Wang, Haiqian, E-mail: hqwang@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2016-06-15

    Understanding how the defects interact with each other and affect the properties of ZnO:Al films is very important for improving their performance as a transparent conductive oxide (TCO). In the present work, we studied the effects of hydrogen annealing on the structural, optical and electrical properties of ZnO:Al films prepared by magnetron sputtering. High resolution transmission electron microscopy observations reveal that annealing at ∼300 {sup o}C induces the formation of partial dislocations (PD) and stacking faults (SF), which disrupt the lattice periodicity leading to decreased grain size. Annealing at temperatures above ∼500 {sup o}C can remove the PD and SF, but large number of zinc vacancies will be generated. Our results show that when films are annealed at ∼500 {sup o}C, the oxygen-related defects (interstitials O{sub i}, etc.) in the as-grown films can be remarkably removed or converted, which lead to increments in the carrier concentration, mobility, and the transmittance in the visible range. At annealing temperatures above 550 {sup o}C, the hydrogen etching effect becomes predominant, and Al donors are deactivated by zinc vacancies. We also find an abnormal endothermic process by thermal analysis and an abnormal increase in the resistivity during heating the sample under hydrogen atmosphere, based on which the interaction of O{sub i} with the defects (mainly Al donors and PD) is discussed. It is also demonstrated that by annealing the as-grown AZO films at ∼500 {sup o}C under hydrogen atmosphere, high performance TCO films with a low resistivity of 4.48 × 10{sup −4} Ωcm and high transmittance of above 90% in the visible light are obtained.

  11. The study of 'microsurfaces' using thermal desorption spectroscopy

    Science.gov (United States)

    Thomas, M. E.; Poppa, H.; Pound, G. M.

    1979-01-01

    The use of a newly combined ultrahigh vacuum technique for studying continuous and particulate evaporated thin films using thermal desorption spectroscopy (TDS), transmission electron microscopy (TEM), and transmission electron diffraction (TED) is discussed. It is shown that (1) CO thermal desorption energies of epitaxially deposited (111) Ni and (111) Pd surfaces agree perfectly with previously published data on bulk (111) single crystal, (2) contamination and surface structural differences can be detected using TDS as a surface probe and TEM as a complementary technique, and (3) CO desorption signals from deposited metal coverages of one-thousandth of a monolayer should be detectable. These results indicate that the chemisorption properties of supported 'microsurfaces' of metals can now be investigated with very high sensitivity. The combined use of TDS and TEM-TED experimental methods is a very powerful technique for fundamental studies in basic thin film physics and in catalysis.

  12. The improved Hydrogen Storage Performances of the Multi-Component Composite: 2Mg(NH22–3LiH–LiBH4

    Directory of Open Access Journals (Sweden)

    Han Wang

    2015-07-01

    Full Text Available 2Mg(NH22–3LiH–LiBH4 composite exhibits an improved kinetic and thermodynamic properties in hydrogen storage in comparison with 2Mg(NH22–3LiH. The peak temperature of hydrogen desorption drops about 10 K and the peak width shrinks about 50 K compared with the neat 2Mg(NH22–3LiH. Its isothermal dehydrogenation and re-hydrogenation rates are respectively 2 times and 18 times as fast as those of 2Mg(NH22–3LiH. A slope desorption region with higher equilibrium pressure is observed. By means of X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and nuclear magnetic resonance (NMR analyses, the existence of Li2BNH6 is identified and its roles in kinetic and thermodynamic enhancement are discussed.

  13. Erbium hydride thermal desorption : controlling kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2007-08-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report show that hydride film processing parameters directly impact thermal stability. Issues to be addressed include desorption kinetics for dihydrides and trihydrides, and the effect of film growth parameters, loading parameters, and substrate selection on desorption kinetics.

  14. Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

    Science.gov (United States)

    Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

    2017-02-22

    In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg2Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg2Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H2 within 10 min at 423 K and release 3.1 wt % H2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol(-1). The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg2Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg2Ni and Mg2NiH4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

  15. Electrical and Surface Properties of InAs/InSb Nanowires Cleaned by Atomic Hydrogen.

    Science.gov (United States)

    Webb, James L; Knutsson, Johan; Hjort, Martin; Gorji Ghalamestani, Sepideh; Dick, Kimberly A; Timm, Rainer; Mikkelsen, Anders

    2015-08-12

    We present a study of InAs/InSb heterostructured nanowires by X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and in-vacuum electrical measurements. Starting with pristine nanowires covered only by the native oxide formed through exposure to ambient air, we investigate the effect of atomic hydrogen cleaning on the surface chemistry and electrical performance. We find that clean and unreconstructed nanowire surfaces can be obtained simultaneously for both InSb and InAs by heating to 380 ± 20 °C under an H2 pressure 2 × 10(-6) mbar. Through electrical measurement of individual nanowires, we observe an increase in conductivity of 2 orders of magnitude by atomic hydrogen cleaning, which we relate through theoretical simulation to the contact-nanowire junction and nanowire surface Fermi level pinning. Our study demonstrates the significant potential of atomic hydrogen cleaning regarding device fabrication when high quality contacts or complete control of the surface structure is required. As hydrogen cleaning has recently been shown to work for many different types of III-V nanowires, our findings should be applicable far beyond the present materials system.

  16. Effect of hydrogen on mechanical properties of β-titanium alloys

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    Conflicting opinions exist in the literature on the manner in which .... Schematic representation of the concept applied to hydrogen charging. ... Literature data except for Ti 13–11–3 (after Hol- man et al 1965) are shown without data points and represent pure β- titanium (solid lines) and pure α- titanium (dashed lines).

  17. Novel PdAgCu ternary alloy: Hydrogen permeation and surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Tarditi, Ana M.; Braun, Fernando [Instituto de Investigaciones en Catalisis y Petroquimica (FIQ, UNL-CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina); Cornaglia, Laura M., E-mail: lmcornag@fiq.unl.edu.ar [Instituto de Investigaciones en Catalisis y Petroquimica (FIQ, UNL-CONICET), Santiago del Estero 2829, 3000 Santa Fe (Argentina)

    2011-05-15

    Dense PdAgCu ternary alloy composite membranes were synthesized by the sequential electroless plating of Pd, Ag and Cu on top of both disk and tubular porous stainless steel substrates. X-ray diffraction and scanning electron microscopy were employed to study the structure and morphology of the tested samples. The hydrogen permeation performance of these membranes was investigated over a 350-450 deg. C temperature range and a trans-membrane pressure up to 100 kPa. After annealing at 500 deg. C in hydrogen stream followed by permeation experiments, the alloy layer presented a FCC crystalline phase with a bulk concentration of 68% Pd, 7% Ag and 25% Cu as revealed by EDS. The PdAgCu tubular membrane was found to be stable during more than 300 h on hydrogen stream. The permeabilities of the PdAgCu ternary alloy samples were higher than the permeabilities of the PdCu alloy membranes with a FCC phase. The co-segregation of silver and copper to the membrane surface was observed after hydrogen permeation experiments at high temperature as determined by XPS.

  18. Soil properties and elements other than hydrogen that can affect the ...

    African Journals Online (AJOL)

    A neutron water meter (NWM) operates on the principle that emitted high-energy neutrons are thermalised by elastic collisions with atomic nuclei present in soil, such as that of the hydrogen atom. Thermalised neutrons, however, are affected by other nuclear-matter interactions such as their capture by soil elements and ...

  19. Interfacial Properties of an Ir/TiO2 System and Their Relevance in Crotonaldehyde Hydrogenation

    NARCIS (Netherlands)

    López Granados, M.; Melián-Cabrera, I.; Aguirre, M.C.; Reyes, P.; Fierro, J.L.G.

    2002-01-01

    Titania-supported iridium catalysts were prereduced in a hydrogen flow at 473 K (LT) and 723 K (HT). Metal particle sizes determined by H2 chemisorption and by direct observation of metal particles by transmission electron microscopy were quite similar for LT treatment, and close to 3.0 nm. For the

  20. Physical properties of Fe doped In{sub 2}O{sub 3} magnetic semiconductor annealed in hydrogen at different temperature

    Energy Technology Data Exchange (ETDEWEB)

    Baqiah, H. [Superconductors and Thin Film Laboratory, Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Ibrahim, N.B., E-mail: baayah@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Halim, S.A., E-mail: ahalim@upm.edu.my [Superconductors and Thin Film Laboratory, Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Chen, S.K.; Lim, K.P.; Kechik, M.M. Awang [Superconductors and Thin Film Laboratory, Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2016-03-01

    The effects of hydrogen-annealing at different temperatures (300, 400, 500 and 600 °C) on physical properties of In{sub 2−x}Fe{sub x}O{sub 3} (x=0.025) thin film were investigated. The structural measurement using XRD shows that the film has a single In{sub 2}O{sub 3} phase structure when annealed in hydrogen at 300–500 °C, however when annealed in hydrogen at 600 °C the film has a mixed phase structure of In{sub 2}O{sub 3} and In phases. The electrical measurements show that the carrier concentrations of the films decrease with the increase of hydrogen-annealing temperature in the range 300–500 °C. The optical band gap of the films decreases with increasing hydrogen-annealing temperatures. The saturation magnetisation, Ms, and coercivity of films increase with the increment of hydrogen annealing temperature. The film annealed at 300 °C has the lowest resistivity, ρ=0.03 Ω cm, and the highest carrier concentrations, n=6.8×10{sup 19} cm{sup −3}, while film annealed at 500 °C has both good electrical (ρ=0.05 Ω.cm and n=2.2×10{sup 19} cm{sup −3}) and magnetic properties, Ms=21 emu/cm{sup -3}. - Highlights: • Physical properties of films were sensitive to hydrogen-annealing temperature. • Magnetisation, Ms, of films increased with increase of hydrogen annealing temperature. • Film annealed in hydrogen at 300 °C has the lowest resistivity, ρ=0.03 Ω cm. • Film annealed in hydrogen at 600 °C has highest magnetisation, Ms=30 emu/cm{sup 3}.

  1. Weak Intermolecular Hydrogen Bonds with Fluorine: Detection and Implications for Enzymatic/Chemical Reactions, Chemical Properties, and Ligand/Protein Fluorine NMR Screening.

    Science.gov (United States)

    Dalvit, Claudio; Vulpetti, Anna

    2016-05-23

    It is known that strong hydrogen-bonding interactions play an important role in many chemical and biological systems. However, weak or very weak hydrogen bonds, which are often difficult to detect and characterize, may also be relevant in many recognition and reaction processes. Fluorine serving as a hydrogen-bond acceptor has been the subject of many controversial discussions and there are different opinions about it. It now appears that there is compelling experimental evidence for the involvement of fluorine in weak intramolecular or intermolecular hydrogen bonds. Using established NMR methods, we have previously characterized and measured the strengths of intermolecular hydrogen-bond complexes involving the fluorine moieties CH2 F, CHF2 , and CF3 , and have compared them with the well-known hydrogen-bond complex formed between acetophenone and the strong hydrogen-bond donor p-fluorophenol. We now report evidence for the formation of hydrogen bonds involving fluorine with significantly weaker donors, namely 5-fluoroindole and water. A simple NMR method is proposed for the simultaneous measurement of the strengths of hydrogen bonds between an acceptor and a donor or water. Important implications of these results for enzymatic/chemical reactions involving fluorine, for chemical and physical properties, and for ligand/protein (19) F NMR screening are analyzed through experiments and theoretical simulations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Hydrogen storage and stability properties of Pd-Pt solid-solution nanoparticles revealed via atomic and electronic structure.

    Science.gov (United States)

    Kumara, Loku Singgappulige Rosantha; Sakata, Osami; Kobayashi, Hirokazu; Song, Chulho; Kohara, Shinji; Ina, Toshiaki; Yoshimoto, Toshiki; Yoshioka, Satoru; Matsumura, Syo; Kitagawa, Hiroshi

    2017-11-06

    Bimetallic Pd1-x Pt x solid-solution nanoparticles (NPs) display charging/discharging of hydrogen gas, which has relevance for fuel cell technologies; however, the constituent elements are immiscible in the bulk phase. We examined these material systems using high-energy synchrotron X-ray diffraction, X-ray absorption fine structure and hard X-ray photoelectron spectroscopy techniques. Recent studies have demonstrated the hydrogen storage properties and catalytic activities of Pd-Pt alloys; however, comprehensive details of their structural and electronic functionality at the atomic scale have yet to be reported. Three-dimensional atomic-scale structure results obtained from the pair distribution function (PDF) and reverse Monte Carlo (RMC) methods suggest the formation of a highly disordered structure with a high cavity-volume-fraction for low-Pt content NPs. The NP conduction band features, as extracted from X-ray absorption near-edge spectra at the Pd and Pt L III -edge, suggest that the Pd conduction band is filled by Pt valence electrons. This behaviour is consistent with observations of the hydrogen storage capacity of these NPs. The broadening of the valence band width and the down-shift of the d-band centre away from the Fermi level upon Pt substitution also provided evidence for enhanced stability of the hydride (ΔH) features of the Pd1-x Pt x solid-solution NPs with a Pt content of 8-21 atomic percent.

  3. Modification of the electronic properties of Au/molecule/Pd junctions by adsorbed hydrogen: a DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Kucera, Jan; Gross, Axel [Institut fuer Theoretische Chemie, Universitaet Ulm, D-89069 Ulm (Germany)

    2011-07-01

    Metal-molecule-metal contacts assembled from a Pd monolayer deposited on a Au-supported self-assembled monolayer (SAM) of 4-mercaptopyridine or 4-aminothiophenol were recently achieved by means of an electrochemical approach. Subsequent photoelectron spectroscopy showed a strongly reduced Pd density of states (DOS) at the Fermi energy. This phenomenon is still not fully comprehended, however, its understanding is crucial for the use of the sandwich design as a platform for future nanoelectronics. Periodic density functional theory (DFT) calculation revealed that the dehydrogenation of the amino group and the subsequent strong bonding of the remaining nitrogen atom to the Pd layer could explain the observed modification of the DOS. We have now extended this study in order to clarify the role of hydrogen atoms for the electronic properties of the Pd layers. In equilibrium, these layers should always show a considerable hydrogen coverage in an aqueous environment. Our calculations demonstrate that indeed the adsorbed hydrogen atoms significantly modify the electronic structure of the Pd layers.

  4. Special structures and properties of hydrogen nanowire confined in a single walled carbon nanotube at extreme high pressure

    Directory of Open Access Journals (Sweden)

    Yueyuan Xia

    2012-06-01

    Full Text Available Extensive ab initio molecular dynamics simulations indicate that hydrogen can be confined in single walled carbon nanotubes to form high density and high pressure H2 molecular lattice, which has peculiar shell and axial structures depending on the density or pressure. The band gap of the confined H2 lattice is sensitive to the pressure. Heating the system at 2000K, the H2 lattice is firstly melted to form H2 molecular liquid, and then some of the H2 molecules dissociate accompanied by drastic molecular and atomic reactions, which have essential effect on the electronic structure of the hydrogen system. The liquid hydrogen system at 2000K is found to be a particular mixed liquid, which consists of H2 molecules, H atoms, and H-H-H trimers. The dissociated H atoms and the trimers in the liquid contribute resonance electron states at the Fermi energy to change the material properties substantially. Rapidly cooling the system from 2000K to 0.01 K, the mixed liquid is frozen to form a mixed solid melt with a clear trend of band gap closure. It indicates that this solid melt may become a superconducting nanowire when it is further compressed.

  5. Enamel properties after tooth bleaching with hydrogen/carbamide peroxides in association with a CPP-ACP paste.

    Science.gov (United States)

    de Vasconcelos, Adriana Alcantara Meira; Cunha, Ana Gabriela Gama; Borges, Boniek Castillo Dutra; Vitoriano, Jussier de Oliveira; Alves-Júnior, Clodomiro; Machado, Cláudia Tavares; dos Santos, Alex José Souza

    2012-07-01

    This study evaluated the impact of bleaching teeth using blends of a CPP-ACP paste (MI Paste; MI) and carbamide/hydrogen peroxides in different proportions on surface properties of bleached enamel. Ninety bovine incisors were bleached with 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), MI and blends of HP or CP:MI at three proportions (1:1, 2:1, 1:2). Hardness and roughness were measured at baseline and after bleaching. Enamel morphology was evaluated by Scanning Electron Microscopy (SEM). The data were analyzed by two-way ANOVA for repeated measurements and Tukey's test. Most of the samples bleached with MI in combination with peroxides presented increased hardness and roughness which were associated to mineral deposition, as observed by SEM images. Blends with higher fractions of MI did not offer superior benefits. The use of a CPP-ACP paste mixed to carbamide/hydrogen peroxides can decrease adverse side-effects from tooth bleaching on an enamel surface.

  6. Tuning the properties of a complex disordered material: Full factorial investigation of PECVD-grown amorphous hydrogenated boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Nordell, Bradley J.; Keck, Christopher L.; Nguyen, Thuong D.; Caruso, A.N. [Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Purohit, Sudhaunshu S. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Lanford, William A. [Department of Physics, University at Albany, Albany, NY 12222 (United States); Dutta, Dhanadeep; Gidley, David [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Henry, Patrick; King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, OR 97124 (United States); Paquette, Michelle M., E-mail: paquettem@umkc.edu [Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

    2016-04-15

    A multiresponse 2{sup 5} full factorial experiment is performed to investigate the effects of growth conditions (temperature, power, pressure, total flow rate, partial precursor flow rate) on the chemical, mechanical, dielectric, electronic, and charge transport properties of thin-film amorphous hydrogenated boron carbide (a-B{sub x}C:H{sub y}) grown by plasma-enhanced chemical vapor deposition (PECVD) from ortho-carborane. The main and interaction effects are determined and discussed, and the relationships between properties are investigated via correlation analysis. The process condition with the strongest influence on growth rate is pressure, followed by partial precursor flow rate, with low pressure and high partial flow rate conditions yielding the highest growth rates. The atomic concentration of hydrogen (at.% H) and density are controlled primarily by temperature and power, with low temperature and power conditions leading to relatively soft, hydrogen-rich, low-density, porous films, and vice versa. The B/C ratio is controlled by temperature, power, pressure, and the power*pressure interaction, and is uncorrelated to hydrogen concentration. Thin-film dielectric and electronic structure properties, including high-frequency dielectric constant (ε{sub 1}), low-frequency/total dielectric constant (κ), optical band gap (E{sub Tauc}/E{sub 04}), and Urbach energy (E{sub U}), are correlated strongly with at.% H, and weakly to moderately with B/C ratio. These properties are dominated by the influence of temperature, with a second significant influence from the power*pressure interaction. The interaction of power and pressure leads to two opposite growth regimes—high power and high pressure or low power and low pressure—that can produce a-B{sub x}C:H{sub y} films with similar dielectric or electronic structure properties. Charge transport properties also show a correlation with at.% H and B/C, but not with the electronic structure and disorder parameters, which

  7. Hydrogenation disproportionation desorption and recombination (HDDR) studies on direct-reduced Nd{sub 15}Fe{sub 77{minus}x}B{sub 8}Ga{sub x} powders

    Energy Technology Data Exchange (ETDEWEB)

    Burkhardt, C.; Harris, I.R. [Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials; Steinhorst, M. [Elektro-Thermit GmbH, Essen (Germany)

    1995-11-01

    Direct-reduced Nd-Fe-B powders with additions of 1.0% and 2.0% Ga were treated by the HDDR process at temperatures between 770 C and 900 C in order to optimize the processing parameters. The microstructures of the powders were investigated by scanning electron microscopy (SEM) on rotary forged Al bonded samples. The investigation of the magnetic properties was carried out on wax-bonded samples on a vibrating sample magnetometer (VSM). It was found that the direct-reduced Nd-Fe-B powders containing Ga additions show significantly increased intrinsic coercivities of up to 895 kA/m compared to those of the ternary alloy or those of powders with Zr additions. The remanence appears to be, for both Nd{sub 15}Fe{sub 76}B{sub 8}Ga{sub 1} and Nd{sub 15}Fe{sub 75}B{sub 8}Ga{sub 2}, relatively constant over a processing temperature range of {approximately}50 C with Nd{sub 15}Fe{sub 76}B{sub 8}Ga{sub 1} exhibiting higher values of up to 680 mT. The disproportionation time has a significant influence on the magnetic properties of the material, higher processing temperatures requiring shorter times in the disproportionated state, lower temperatures longer times. Under the conditions employed in these experiments, the HDDR treatment removes existing anisotropy in the as-received coarse grain material, thus leading to predominantly isotropic behavior.

  8. Hydrogen Adsorption Properties of Nano- and Microstructures of ZnO

    Directory of Open Access Journals (Sweden)

    Rizwan Wahab

    2013-01-01

    Full Text Available Nanoparticles, microflowers, and microspheres of zinc oxide have been synthesized in a large quantity via solution process at low temperature and were tested for the hydrogen adsorption studies. The experiments were carried out using Sievert’s apparatus which resulted in highest hydrogen adsorption value for nanoparticles is ~1.220 wt%, whereas for microflower composed with thin sheets value reduced (~1.011 wt% but in case of microspheres composed with nanoparticles having below one wt% (~0.966 wt%. The FE-SEM and XRD clarify that the obtained products are crystalline with wurtzite phase. Including morphological and crystalline characterization, the surface area of the prepared nano- and microstructures was observed with BET.

  9. Multifunctional porous graphene for nanoelectronics and hydrogen storage: new properties revealed by first principle calculations.

    Science.gov (United States)

    Du, Aijun; Zhu, Zhonghua; Smith, Sean C

    2010-03-10

    The lack of an obvious "band gap" is a formidable hurdle for making a nanotransistor from graphene. Here, we use density functional calculations to demonstrate for the first time that porosity such as evidenced in recently synthesized porous graphene ( http://www.sciencedaily.com/releases/2009/11/091120084337.htm ) opens a band gap. The size of the band gap (3.2 eV) is comparable to most popular photocatalytic titania and graphitic C(3)N(4) materials. In addition, the adsorption of hydrogen on Li-decorated porous graphene is much stronger than that in regular Li-doped graphene due to the natural separation of Li cations, leading to a potential hydrogen storage gravimetric capacity of 12 wt %. In light of the most recent experimental progress on controlled synthesis, these results uncover new potential for the practical application of porous graphene in nanoelectronics and clean energy.

  10. Electric and spectroscopic properties of argon-hydrogen RF microplasma jets at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Souza-Correa, J A; Oliveira, C; Amorim, J [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol-CTBE, Caixa Postal 6170, 13083-970, Campinas, Sao Paulo (Brazil); Gomes, M P, E-mail: jorge.correa@bioetanol.org.b, E-mail: carlos.filho@bioetanol.org.b, E-mail: gomesmp@ita.b, E-mail: jayr.amorim@bioetanol.org.b [Departamento de Fisica, Instituto Tecnologico de Aeronautica-ITA, Praca Marechal Eduardo Gomes 50, 12.228-900, Sao Jose dos Campos, Sao Paulo (Brazil)

    2010-10-06

    Microplasma jets of argon-hydrogen (Ar-H{sub 2}) gas mixture were generated by 144.0 MHz radio-frequency (RF) waves at powers of 5 W, 10 W, 20 W and 50 W. The experimental setup employed creates stable microplasmas at atmospheric pressure from 5.0 mm up to 20.0 mm visual glow lengths. We have determined the rms voltages, the rms electric currents and the power absorptions of these microplasma jets. By making use of optical spectroscopy, the emission spectra of Ar-H{sub 2} microplasma jets were recorded in the range 3060-8200 A, in order to estimate the axial distribution profiles of electron density, rotational temperature, excitation temperature and hydrogen atomic temperature.

  11. Evaluation of the Relative Hydrogen Embrittlement Susceptibility of ESR 4340 and Its Heat Treat Distortion Properties

    Science.gov (United States)

    1982-09-01

    of a tensile load. This was accomplished by modifying a special loading fixture developed at METTEK Laboratories for Charpy -sized specimens. Two...with regard to ballistic impact resistance, it becomes advisable to direct a program at improving the resistance of ESR steels to hydrogen...30332 1 ATTN: Dr. J. T. Berry Lukens Steel Company, Coatesville, PA 19320 1 ATTN: Dr. R. S. Swift Republic Steel Corporation, 410 Oberlin Avenue

  12. Atomic Hydrogen Properties of AGN Host Galaxies: HI in 16 NUclei of GAlaxies (NUGA) Sources

    OpenAIRE

    S. de Haan; Schinnerer, E.; Mundell, C. G.; Garcia-Burillo, S.; Combes, F.

    2007-01-01

    We present a comprehensive spectroscopic imaging survey of the distribution and kinematics of atomic hydrogen (HI) in 16 nearby spiral galaxies hosting low luminosity AGN, observed with high spectral and spatial resolution (resolution: ~20 arcsec, 5 km/s) using the NRAO Very Large Array (VLA). The sample contains a range of nuclear types, ranging from Seyfert to star-forming nuclei and was originally selected for the NUclei of GAlaxies project (NUGA) - a spectrally and spatially resolved inte...

  13. Effect of treatment with alkaline hydrogen peroxide associated with extrusion on color and hydration properties of oat hulls

    Directory of Open Access Journals (Sweden)

    Melicia Cintia Galdeano

    2005-01-01

    Full Text Available An incomplete factorial design with three independent variables at three levels of variation was used to evaluate the effect of the treatment with alkaline hydrogen peroxide concomitant with extrusion on some properties of oat hulls. The independent variables were hydrogen peroxide level, feed moisture and extrusion temperature. The dependent variables were water retention capacity (WRC, swollen volume (SV and color. The analysis of variance showed that temperature was the most important variable for the hydration properties. The highest values of WRC and SV were obtained when oat hulls were processed in the condition of 7% hydrogen peroxide, 32% feed moisture and 90ºC extrusion temperature. Modified hulls had a WRC 70% higher and SV 55% higher than the untreated material. The instrumental measure of color was conducted to analyze the modifications promoted due to the treatment in this parameter. The highest value of brightness was obtained with 7% hydrogen peroxide. The modifications in the fibers were accompanied indirectly through hydration properties.Um delineamento fatorial incompleto 3³ foi utilizado para estudar o efeito do tratamento com peróxido de hidrogênio alcalino associado à extrusão sobre algumas propriedades funcionais da fibra da casca de aveia. As variáveis do tratamento avaliadas incluíram teor de peróxido de hidrogênio (%, umidade da amostra (% e temperatura de extrusão (ºC. A análise de variância (ANOVA mostrou que a temperatura foi a variável mais importante para as propriedades de hidratação. Os maiores valores de capacidade de retenção de água (CRA e volume de intumescimento foram obtidos na condição de 7% de peróxido de hidrogênio, 32% de umidade e 90ºC de temperatura, obtendo um incremento de 70% na CRA e 55% no volume de intumescimento. A medida instrumental de cor foi usada para analisar as modificações ocorridas neste parâmetro. O mais alto valor de luminosidade foi alcançado com maior n

  14. Effects of Nd-addition on the structural, hydrogen storage, and electrochemical properties of C14 metal hydride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Nei, J.; Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Ng, K.Y.S. [Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States)

    2015-10-25

    Nd-addition to the AB{sub 2}-based alloy Ti{sub 12}Zr{sub 22.8−x}V{sub 10}Cr{sub 7.5}Mn{sub 8.1}Co{sub 7.0}Ni{sub 32.2}Al{sub 0.4}Nd{sub x} is studied for its effects on the structure, gaseous-phase hydrogen storage, and electrochemical properties. This study follows a series of Cu, Mo, Fe, Y, Si, and La doping studies in similar AB{sub 2}-based alloys. Limited solubility of Nd in the main Laves phase promotes the formation of secondary phases (AB and Zr{sub 7}Ni{sub 10}) to provide catalytic effects and synergies for improved capacity and high-rate dischargeability (HRD) performance. The main C14 storage phase has smaller lattice constants and cell volumes, and these effects reduce the storage capacity at higher Nd levels. Different hydrogen absorption mechanisms can occur in these multi-component, multi-phase alloys depending on the interfaces of the phases, and they have effects on the alloy properties. Higher Nd-levels improve the HRD performance despite having lower bulk diffusion and surface exchange current. Magnetic susceptibility measurements indicate large percentage of larger metallic nickel clusters are present in the surface oxide of alloys with higher Nd-content, and AC impedance studies show very low charge-transfer resistance with high catalytic capability in the alloys. The −40 °C charge-transfer resistance of 8.9 Ω g in this Nd-series of alloys is the lowest measured out of the studies investigating doped AB{sub 2}-based MH alloys for improved low-temperature characteristics. The improvement in HRD and low-temperature performance appears to be related to the proportion of the highly catalytic NdNi-phase at the surface, which must offset the increased bulk diffusion resistance in the alloy. - Graphical abstract: Schematics of hydrogen flow and corresponding PCT isotherms in funneling mode. - Highlights: • Structural and hydrogen storage properties of Nd-substituted AB{sub 2} metal hydride are reported. • Nd contributes to the lowest

  15. Direct probing of micromechanical properties of hydrogen-bonded layer-by-layer microcapsule shells with different chemical compositions.

    Science.gov (United States)

    Lisunova, Milana O; Drachuk, Irina; Shchepelina, Olga A; Anderson, Kyle D; Tsukruk, Vladimir V

    2011-09-06

    The mechanical properties of hydrogen-bonded layer-by-layer (LbL) microcapsule shells constructed from tannic acid (TA) and poly(vinylpyrrolidone) (PVPON) components have been studied in both the dry and swollen states. In the dry state, the value of the elastic modulus was measured to be within 0.6-0.7 GPa, which is lower than the typical elastic modulus for electrostatically assembled LbL shells. Threefold swelling of the LbL shells in water results in a significant reduction of the elastic modulus to values well below 1 MPa, which is typical value seen for highly compliant gel materials. The increase of the molecular weight of the PVPON component from 55 to 1300 kDa promotes chain entanglements and causes a stiffening of the LbL shells with a more than 2-fold increase in elastic modulus value. Moreover, adding a polyethylenimine prime layer to the LbL shell affects the growth of hydrogen-bonded multilayers which consequently results in dramatically stiffer, thicker, and rougher LbL shells with the elastic modulus increasing by more than an order of magnitude, up to 4.3 MPa. An alternation of the elastic properties of very compliant hydrogen-bonded shells by variation of molecular weight is a characteristic feature of weakly bonded LbL shells. Such an ability to alter the elastic modulus in a wide range is critically important for the design of highly compliant microcapsules with tunable mechanical stability, loading ability, and permeability. © 2011 American Chemical Society

  16. Potential mesogens based on pyridine derivatives: The geometric structure, conformational properties and characteristics of intermolecular hydrogen bonds

    Science.gov (United States)

    Fedorov, Mikhail S.; Giricheva, Nina I.; Shpilevaya, Kseniya E.; Lapykina, Elena A.; Syrbu, Svetlana A.

    2017-03-01

    Conformational properties of the main part (excluding sbnd OC3H7 radicals) of the p-n-propyloxybenzoic (A1) and p-n-propyloxycinnamic (A2) acids molecules (relating to mesomorphic compounds) as well as p-n-propyloxybenzoic acid pyridine ester (B1) and p-n-propyloxyphenylazopyridine (B2) molecules (relating to non-mesomorphic compounds) were studied by DFT(B3LYP)/cc-pVTZ method. It was shown that the main parts of A1 and A2 acids are rigid. The barrier to internal rotation of pyridine fragment in the B1 and B2 molecules depends on the nature of the bridging group. It was determined that all studied A1⋯B1, A2⋯B1 and A2⋯B2 complexes are characterized by a strong hydrogen bond. The binding energy of complexes (≈14 kcal/mol, with BSSE corrections, DFT(B97D)/6-311++G**) exceeds the energy per hydrogen bond in the corresponding acid dimers (≈10 kcal/mol). The structural non-rigidity of A⋯B complexes is mainly caused by possibility of sbnd OC3H7 radicals internal rotation and A and B molecules rotation about the (H)O⋯N line. The characteristics of intermolecular hydrogen bonds were determined by NBO-analysis. The obtained results indicate that examined complexes correspond to the basic requirements to mesogen molecular forms. The thermodynamic functions of the gas-phase complexation reactions (idealized model of the complexes formation in the condensed state) were calculated. Preliminary studies of mesogen-non-mesogen A1⋯B2 system by differential scanning calorimetry and polarizing optical microscopy, showed that it has mesomorphic properties.

  17. Superior hydrogen storage and electrochemical properties of Mg(x)Ni(100-x)/Pd films at room temperature.

    Science.gov (United States)

    Liu, Tong; Cao, Yurong; Xin, Gongbiao; Li, Xingguo

    2013-10-07

    The Mg(x)Ni(100-x) films of 100 nm have been prepared by magnetron co-sputtering Mg and Ni targets, and a Pd layer of 10 nm was deposited on these films by magnetron sputtering a Pd target. Mg2Ni and MgNi2 are directly generated during the co-sputtering process in the Mg84Ni16/Pd and Mg48Ni52/Pd films. The hydrogen storage properties of the films under 0.1 MPa H2 at 298 K were investigated. The hydrogenation of the Mg84Ni16/Pd film saturates within 45 s and exhibits the faster absorption kinetics compared with Mg94Ni6/Pd and Mg48Ni52/Pd films. The electrochemical properties of the Mg(x)Ni(100-x)/Pd films were investigated in 6 M KOH with a three-electrode cell. The Mg84Ni16/Pd film can be activated just at the first cycle. The maximum discharge capacity of the Mg84Ni16/Pd film is 482.7 mAh g(-1), the highest among these films.

  18. Desorption of H atoms from graphite (0001) using XUV free electron laser pulses

    DEFF Research Database (Denmark)

    Siemer, B.; Olsen, Thomas; Hoger, T.

    2010-01-01

    , and identifies the highest vibrational state in the adsorbate potential as a major source for the slow atoms. It is evident that multiple electron scattering processes are required for this desorption. A direct electronic excitation of a repulsive hydrogen-carbon bond seems not to be important....

  19. Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

    NARCIS (Netherlands)

    Griessen, R.P.; Strohfeldt, N.; Giessen, H.

    2015-01-01

    Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and

  20. Hydrogen Storage in Magnesium Clusters: Quantum Chemical Study

    NARCIS (Netherlands)

    Wagemans, R.W.P.; van Lenthe, J.H.|info:eu-repo/dai/nl/068417942; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; van Dillen, A.J.|info:eu-repo/dai/nl/111157625; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2005-01-01

    Magnesium hydride is cheap and contains 7.7 wt % hydrogen, making it one of the most attractive hydrogen storage materials. However, thermodynamics dictate that hydrogen desorption from bulk magnesium hydride only takes place at or above 300 degrees C, which is a major impediment for practical

  1. Adsorption of hydrogen on clean and modified magnesium films

    DEFF Research Database (Denmark)

    Johansson, Martin; Ostenfeld, Christopher Worsøe; Chorkendorff, Ib

    2006-01-01

    The sticking of hydrogen on 400 A thick magnesium films, grown under ultrahigh vacuum conditions, have been measured under conditions relevant for hydrogen storage, i.e., elevated temperatures and pressures. A model which describes the hydrogenation and desorption kinetics of the pure magnesium f...

  2. Hydrogen impurity in SrTiO{sub 3}: structure, electronic properties and migration

    Energy Technology Data Exchange (ETDEWEB)

    Villamagua, Luis [Grupo de Fisica de Cristales, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Barreto, Rafael [Facultad de IngenierIa Civil, Escuela Politecnica Nacional, Apartado 14-01-2759, Quito (Ecuador); Procel, Luis Miguel [Departamento de Quimica, Colegio Politecnico, Universidad San Francisco de Quito, Apartado 17-12-841, Quito (Ecuador); Stashans, Arvids [Grupo de Fisica de Cristales, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

    2007-03-15

    The present paper reports a computational investigation of the geometry and electronic structure as well as the migration of a hydrogen impurity in the cubic SrTiO{sub 3} crystal. The study is done using an approach based on the Hartree-Fock theory and developed for periodic systems. It is found that the H impurity forms the so-called OH group at the equilibrium. Analysis of electron density within the defective region implies the enhancement in covalent chemical bonding. A possible defect migration has been also investigated.

  3. Linear and nonlinear optical properties of a hydrogenic donor in lens-shaped quantum dots

    Science.gov (United States)

    Vahdani, M. R. K.; Rezaei, G.

    2009-08-01

    Optical transitions in a Lens-Shaped Quantum Dot (LSD) are investigated in the presence of a hydrogenic impurity. The electronic wave functions are obtained analytically and the energy eigenvalues are calculated numerically. The density matrix formulation with the intersubband relaxation are used to evaluate the (linear and third order nonlinear) absorption coefficient (AC) and the change in the refractive indices (RI) analytically. The effect of the size of the LSD and optical intensity on the AC and RI are investigated. It is found that AC and RI are strongly affected by the optical intensity and the size of the LSD.

  4. New perspectives in vacuum high voltage insulation. II. Gas desorption

    CERN Document Server

    Diamond, W T

    1998-01-01

    An examination has been made of gas desorption from unbaked electrodes of copper, niobium, aluminum, and titanium subjected to high voltage in vacuum. It has been shown that the gas is composed of water vapor, carbon monoxide, and carbon dioxide, the usual components of vacuum outgassing, plus an increased yield of hydrogen and light hydrocarbons. The gas desorption was driven by anode conditioning as the voltage was increased between the electrodes. The gas is often desorbed as microdischarges-pulses of a few to hundreds of microseconds-and less frequently in a more continuous manner without the obvious pulsed structure characteristic of microdischarge activity. The quantity of gas released was equivalent to many monolayers and consisted mostly of neutral molecules with an ionic component of a few percent. A very significant observation was that the gas desorption was more dependent on the total voltage between the electrodes than on the electric field. It was not triggered by field-emitted electrons but oft...

  5. Crystal growth, structural, optical, thermal and dielectric properties of lithium hydrogen oxalate monohydrate single crystal

    Science.gov (United States)

    Chandran, Senthilkumar; Paulraj, Rajesh; Ramasamy, P.

    2017-11-01

    The vibrational groups of the lithium hydrogen oxalate monohydrate have been investigated by FTIR and FT- Raman analyses. It has low absorbance in the UV-Vis-NIR region. The laser damage threshold study confirms that the material withstands upto 30 mJ with time of 7 s, after that circular dot damage is seen on the surface. The dark region of the surface damage spot occurs due to the thermal effects. The material is thermally stable upto 93 °C and there is no weight loss below this temperature. The dielectric studies were carried out at the frequency regions of 1 kHz-1 MHz and different temperatures from 40 °C to 80 °C. Semi-organic non-linear optical (NLO) single crystal lithium hydrogen oxalate monohydrate has been grown by slow evaporation solution growth technique. The Hirshfeld surface analysis was performed to understand the different intermolecular interactions in the title compound. The fingerprint plots contain the highest portion of H⋯O/O⋯H (48.3%) interactions.

  6. The synthesis and hydrogen storage properties of a MgH(2) incorporated carbon aerogel scaffold.

    Science.gov (United States)

    Zhang, Shu; Gross, Adam F; Van Atta, Sky L; Lopez, Maribel; Liu, Ping; Ahn, Channing C; Vajo, John J; Jensen, Craig M

    2009-05-20

    A new approach to the incorporation of MgH2 in the nanometer-sized pores of a carbon aerogel scaffold was developed, by infiltrating the aerogel with a solution of dibutylmagnesium (MgBu2) precursor, and then hydrogenating the incorporated MgBu2 to MgH2. The resulting impregnated material showed broad x-ray diffraction peaks of MgH2. The incorporated MgH2 was not visible using a transmission electron microscope, which indicated that the incorporated hydride was nanosized and confined in the nanoporous structure of the aerogel. The loading of MgH2 was determined as 15-17 wt%, of which 75% is reversible over ten cycles. Incorporated MgH2 had >5 times faster dehydrogenation kinetics than ball-milled activated MgH2, which may be attributed to the particle size of the former being smaller than that of the latter. Cycling tests of the incorporated MgH(2) showed that the dehydrogenation kinetics are unchanged over four cycles. Our results demonstrate that confinement of metal hydride materials in a nanoporous scaffold is an efficient way to avoid aggregation and improve cycling kinetics for hydrogen storage materials.

  7. Enhanced dehydrogenation of hydrazine bisborane for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Leigang [Department of Materials Science, Fudan University, Shanghai 200433 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Tan, Yingbin; Tang, Ziwei; Xia, Guanglin; Yuan, Feng [Department of Materials Science, Fudan University, Shanghai 200433 (China); Li, Qian, E-mail: shuliqian@shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Yu, Xuebin, E-mail: yuxuebin@fudan.edu.cn [Department of Materials Science, Fudan University, Shanghai 200433 (China)

    2014-02-14

    NiCl{sub 2} and CoCl{sub 2} were adopted to enhance the dehydrogenation of hydrazine bisborane (HBB), respectively, of which NiCl{sub 2} showed better performance. By adding 2.0 mol. % NiCl{sub 2}, the dehydrogenation property of HBB was significantly improved, for example, the impurity of NH{sub 3} during the dehydrogenation of HBB was totally suppressed with more than 13.0 wt. % of pure hydrogen evolved. By Kissinger method, the apparent activation energies of the first step for HBB and Ni-doped HBB were calculated to be 143.2 and 60.7 kJ mol{sup −1}, respectively. DSC result showed that the addition of NiCl{sub 2} did not change the enthalpy change of HBB dehydrogenation. Based on theoretical analysis and literature review, the improved dehydrogenation property of HBB was potentially ascribed to the solid state interaction of Ni{sup 2+} with the electronegative N in the NH{sub 2} group of HBB. - Highlights: • NiCl{sub 2} enhanced dehydrogenation of hydrazine bisborane (HBB) was reported. • By adding NiCl{sub 2}, the desorption rate and the hydrogen purity were improved. • A possible explanation was proposed to understand NiCl{sub 2} enhanced desorption of HBB.

  8. Characterizing and optimizing a laser-desorption molecular beam source

    Science.gov (United States)

    Teschmit, Nicole; Długołecki, Karol; Gusa, Daniel; Rubinsky, Igor; Horke, Daniel A.; Küpper, Jochen

    2017-10-01

    The design and characterization of a new laser-desorption molecular beam source, tailored for use in x-ray free-electron laser and ultrashort-pulse laser imaging experiments, is presented. It consists of a single mechanical unit containing all source components, including the molecular-beam valve, the sample, and the fiber-coupled desorption laser, which is movable in five axes, as required for experiments at central facilities. Utilizing strong-field ionization, we characterize the produced molecular beam and evaluate the influence of desorption laser pulse energy, relative timing of valve opening and desorption laser, sample bar height, and which part of the molecular packet is probed on the sample properties. Strong-field ionization acts as a universal probe and allows detecting all species present in the molecular beam, and hence enables us to analyze the purity of the produced molecular beam, including molecular fragments. We present optimized experimental parameters for the production of the purest molecular beam, containing the highest yield of intact parent ions, which we find to be very sensitive to the placement of the desorbed-molecule plumes within the supersonic expansion.

  9. Antibacterial Properties and Mechanism of Activity of a Novel Silver-Stabilized Hydrogen Peroxide.

    Directory of Open Access Journals (Sweden)

    Nancy L Martin

    Full Text Available Huwa-San peroxide (hydrogen peroxide; HSP is a NSF Standard 60 (maximum 8 mg/L(-1 new generation peroxide stabilized with ionic silver suitable for continuous disinfection of potable water. Experiments were undertaken to examine the mechanism of HSP against planktonic and biofilm cultures of indicator bacterial strains. Contact/kill time (CT relationships that achieve effective control were explored to determine the potential utility in primary disinfection. Inhibitory assays were conducted using both nutrient rich media and a medium based on synthetic wastewater. Assays were compared for exposures to three disinfectants (HSP, laboratory grade hydrogen peroxide (HP and sodium hypochlorite at concentrations of 20 ppm (therefore at 2.5 and 5 times the NSF limit for HP and sodium hypochlorite, respectively and at pH 7.0 and 8.5 in dechlorinated tap water. HSP was found to be more or equally effective as hypochlorite or HP. Results from CT assays comparing HSP and HP at different bacterial concentrations with neutralization of residual peroxide with catalase suggested that at a high bacterial concentration HSP, but not HP, was protected from catalase degradation possibly through sequestration by bacterial cells. Consistent with this hypothesis, at a low bacterial cell density residual HSP was more effectively neutralized as less HSP was associated with bacteria and therefore accessible to catalase. Silver in HSP may facilitate this association through electrostatic interactions at the cell surface. This was supported by experiments where the addition of mono (K(+ and divalent (Ca(+2 cations (0.005-0.05M reduced the killing efficacy of HSP but not HP. Experiments designed to distinguish any inhibitory effect of silver from that of peroxide in HSP were carried out by monitoring the metabolic activity of established P. aeruginosa PAO1 biofilms. Concentrations of 70-500 ppm HSP had a pronounced effect on metabolic activity while the equivalent

  10. The thermodynamic properties of the high-pressure superconducting state in the hydrogen-rich compounds

    Science.gov (United States)

    Szcz&şacute; niak, Radosław; Durajski, Artur P.

    2013-11-01

    The ab initio calculations suggest that the superconducting state in CaH6 under the pressure (p) at 150 GPa has the highest critical temperature among the examined hydrogen-rich compounds. For this reason, the relevant thermodynamic parameters of the superconducting state in CaH6 have been determined; a wide range of the Coulomb pseudopotential has been assumed: μ⋆∈. It has been found that: (i) The critical temperature (TC) changes in the range from 243 K to 180 K (ii) The values of the ratio of the energy gap to the critical temperature (RΔ ≡ 2Δ(0)/kBTC) can be found in the range from 5.42 to 5.02. (iii) The ratio of the specific heat jump (ΔC(TC)) to the value of the specific heat in the normal state (CN(TC)), which has been represented by the symbol RC, takes the values from 3.30 to 3.18. (iv) The ratio R≡TC(T)/HC2(0), where HC(0) denotes the critical thermodynamic field, changes from 0.122 to 0.125. The above results mean that even for the strong electron depairing correlations the superconducting state in CaH6 is characterized by a very high value of TC, and the remaining thermodynamic parameters significantly deviate from the predictions of the BCS theory. The study has brought out the expressions that correctly predict the values of the thermodynamic parameters for the superconducting state in CaH6 and for the compounds: SiH4(H2)2, Si2H6, B2H6, SiH4, GeH4, and PtH. Next, in the whole family of the hydrogen-rich compounds, the possible ranges of the values have been determined for TC, RΔ, RC, and RH. It has been found that the maximum value of the critical temperature can be equal to 764 K, which very well correlates with TC for metallic hydrogen (p = 2 TPa). Other parameters (RΔ, RC, and RH) should not deviate from the predictions of the BCS theory more than the analogous parameters for CaH6.

  11. Ag3PO4-TiO2-Graphene Oxide Ternary Composites with Efficient Photodegradation, Hydrogen Evolution, and Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Fu-Jye Sheu

    2018-02-01

    Full Text Available Ag3PO4-TiO2-graphene oxide ternary composite photocatalysts were fabricated by the photocatalytic reduction and ion exchange methods. The properties and photocatalytic activity of the composites were examined, and the photodegradation mechanism was investigated. More TiO2 nanoparticles in the composites were found to improve light absorption, but caused a larger impedance and inferior charge transport. Excess TiO2 nanoparticles distributed over the surfaces of Ag3PO4 and graphene oxide decreased the specific surface area and thus lowered light absorbance. An appropriate TiO2 content enhanced photocatalytic performance. When the molar ratio of Ag3PO4 to TiO2 was 0.6, the highest efficiency in photodegradation, hydrogen production (with a quantum efficiency of 8.1% and a hydrogen evolution rate of 218.7 μmole·g−1·h−1 and bacterial inactivation was achieved. Trapping experiments demonstrated that superoxide radicals and holes are the major active species involved in the photodegradation process.

  12. Ion Impact Energy Distributions and Properties of Amorphous Hydrogenated Carbon Thin Films Deposited in a Self-Biased RF Discharge

    Science.gov (United States)

    Tatsuta, Toshiaki; Tachibana, Kunihide; Tsuji, Osamu

    1994-11-01

    In a self-biased RF discharge in CH4 we have investigated the relationships between the properties of hydrogenated amorphous carbon (a-C:H) film and ion impact energy distributions (IIEDs) measured by retarding-type ion energy analyzer at both parallel-plate electrodes. On the RF electrode a high-energy peak (HEP) dur to the ion beam component was observed in IIED. The height of HEP decreased with increasing pressure at a given self-bias voltage (V dc) and the central energy of HEP increased linearly with V dc at a given pressure. The micro hardness of the film increased in proportion to the total incident ion current (TIIC) and central energy of HEP. The hydrogen content decreased and the surface morphology became fine as the central energy of HEP increased. From Raman and IR absorption spectra it turned out that there was an optimal energy of HEP to increase the content of the sp3 bonding structure in the film.

  13. Prediction of psychotropic properties of lisuride hydrogen maleate by quantitative pharmaco-electroencephalogram.

    Science.gov (United States)

    Itil, T M; Herrmann, W M; Akpinar, S

    1975-07-01

    Based on "quantitative pharmaco-EEG" using computer-analyzed EEG (CEEG) measurements, unknown CNS effects of lisuride hydrogen maleate (LHM) were established. CEEG profiles of LHM in low dosages (less than or equal to 10 mcg) are similar to CNS "inhibitory" compounds, while in higher dosages (25 mcg to 100 mcg) they resemble "psychostimulant" compounds. By measuring the brain function using computer period analysis of cerebral biopotentials, dose-efficacy relations were found (in the range of 25-75 mcg) which suggest the bioavailability of LHM at the CNS level. By comparing the CEEG profiles of LHM with the previously studied compounds, five different clinical uses of LHM were predicted. The pilot trials suggest that LHM may have therapeutic potentials in patients with "aging" and/or organic brain syndromes, and in children with behavioral disturbances.

  14. Impurity doping effects on the orbital thermodynamic properties of hydrogenated graphene, graphane, in Harrison model

    Science.gov (United States)

    Yarmohammadi, Mohsen

    2016-12-01

    Using the Harrison model and Green's function technique, impurity doping effects on the orbital density of states (DOS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of a monolayer hydrogenated graphene, chair-like graphane, are investigated. The effect of scattering between electrons and dilute charged impurities is discussed in terms of the self-consistent Born approximation. Our results show that the graphane is a semiconductor and its band gap decreases with impurity. As a remarkable point, comparatively EHC reaches almost linearly to Schottky anomaly and does not change at low temperatures in the presence of impurity. Generally, EHC and MS increases with impurity doping. Surprisingly, impurity doping only affects the salient behavior of py orbital contribution of carbon atoms due to the symmetry breaking.

  15. Intermolecular and intramolecular hydrogen bonds involving fluorine atoms: implications for recognition, selectivity, and chemical properties.

    Science.gov (United States)

    Dalvit, Claudio; Vulpetti, Anna

    2012-02-06

    A correlation between 19F NMR isotropic chemical shift and close intermolecular F⋅⋅⋅H-X contacts (with X=N or O) has been identified upon analysis of the X-ray crystal structures of fluorinated molecules listed in the Cambridge Structural Database (CSD). An optimal F⋅⋅⋅X distance involving primary and shielded secondary fluorine atoms in hydrogen-bond formation along with a correlation between F⋅⋅⋅H distance and F⋅⋅⋅H-X angle were also derived from the analysis. The hydrogen bonds involving fluorine are relevant, not only for the recognition mechanism and stabilization of a preferred conformation, but also for improvement in the permeability of the molecules, as shown with examples taken from a proprietary database. Results of an analysis of the small number of fluorine-containing natural products listed in the Protein Data Bank (PDB) appear to strengthen the derived correlation between 19F NMR isotropic chemical shift and interactions involving fluorine (also known as the "rule of shielding") and provides a hypothesis for the recognition mechanism and catalytic activity of specific enzymes. Novel chemical scaffolds, based on the rule of shielding, have been designed for recognizing distinct structural motifs present in proteins. It is envisaged that this approach could find useful applications in drug design for the efficient optimization of chemical fragments or promising compounds by increasing potency and selectivity against the desired biomolecular target. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Investigation on Growth, Structural, Spectral, Optical, and Mechanical Properties of an Organic Nonlinear Optical Material: Morpholinium Hydrogen Tartrate

    Directory of Open Access Journals (Sweden)

    R. Renugadevi

    2014-01-01

    Full Text Available Organic nonlinear optical crystal morpholinium hydrogen tartrate (MHT, with molecular formula [C8H15NO7], has been grown by slow evaporation solution technique. Single crystal X-ray diffraction study confirms that MHT crystallizes in orthorhombic system with noncentrosymmetric space group P212121. FTIR spectrum was recorded to identify the various functional groups of MHT. The various kinds of protons and carbons of MHT have been identified using 1H and 13C NMR spectral analyses. The range of optical absorption was ascertained by recording UV-Vis-NIR spectral studies. The TG/DTA studies revealed that the grown crystal is thermally stable up to 159.26°C. The mechanical property of the grown crystal was studied using Vickers microhardness studies. The relative second harmonic generation efficiency of MHT was determined using Kurtz and Perry powder technique; it was observed to be greater than that of KDP crystal.

  17. Tuning electronic properties of fully hydrogenated AlN nanosheets by external electric field: A van der Waals density functional study

    Science.gov (United States)

    Zhang, W. X.; Sun, G. D.; Zhao, L.

    2016-12-01

    In this paper, the structural and electronic properties of two dimensional (2D) fully hydrogenated AlN nanosheets have been investigated by density functional theory computations with van der Waals (vdW) correction. The results demonstrate that there exists strong hydrogen bonding between the nanosheets. Especially, fully hydrogenated AlN monolayer and bilayer nanosheets both have an indirect band gap, irrespective of stacking pattern and thickness. The band gap of fully hydrogenated AlN monolayer and bilayer can be flexibly reduced by applying an external electronic field (E-field), resulting in a semiconductor → metal transition. The results provide many useful insights for the wide applications of AlN nanosheets in electronics and optoelectronics.

  18. Enhanced Hydrogen Generation Properties of MgH2-Based Hydrides by Breaking the Magnesium Hydroxide Passivation Layer

    Directory of Open Access Journals (Sweden)

    Liuzhang Ouyang

    2015-05-01

    Full Text Available Due to its relatively low cost, high hydrogen yield, and environmentally friendly hydrolysis byproducts, magnesium hydride (MgH2 appears to be an attractive candidate for hydrogen generation. However, the hydrolysis reaction of MgH2 is rapidly inhibited by the formation of a magnesium hydroxide passivation layer. To improve the hydrolysis properties of MgH2-based hydrides we investigated three different approaches: ball milling, synthesis of MgH2-based composites, and tuning of the solution composition. We demonstrate that the formation of a composite system, such as the MgH2/LaH3 composite, through ball milling and in situ synthesis, can improve the hydrolysis properties of MgH2 in pure water. Furthermore, the addition of Ni to the MgH2/LaH3 composite resulted in the synthesis of LaH3/MgH2/Ni composites. The LaH3/MgH2/Ni composites exhibited a higher hydrolysis rate—120 mL/(g·min of H2 in the first 5 min—than the MgH2/LaH3 composite— 95 mL/(g·min—without the formation of the magnesium hydroxide passivation layer. Moreover, the yield rate was controlled by manipulation of the particle size via ball milling. The hydrolysis of MgH2 was also improved by optimizing the solution. The MgH2 produced 1711.2 mL/g of H2 in 10 min at 298 K in the 27.1% ammonium chloride solution, and the hydrolytic conversion rate reached the value of 99.5%.

  19. Effects of hydrogen on the structural and optical properties of MoSe2 grown by hot filament chemical vapor deposition

    Science.gov (United States)

    Wang, B. B.; Zhu, M. K.; Levchenko, I.; Zheng, K.; Gao, B.; Xu, S.; Ostrikov, K.

    2017-10-01

    The role of reactive environment and hydrogen specifically in growth and structure of molybdenum selenide (MoSe2) nanomaterials is presently debated, and it is not clear whether hydrogen can promote the growth of MoSe2 sheets and alter their electronic properties. To find efficient, convenient methods for controlling the nucleation, growth and resultant properties of MoSe2 nanomaterials, MoSe2 nanoflakes were synthesized on silicon substrates by hot filament chemical vapor deposition using molybdenum trioxide and selenium powders in pure hydrogen, nitrogen gases and hydrogen-nitrogen mixtures. The structures and composition of synthesized MoSe2 nanoflakes were studied using the advanced characterization instruments including field emission scanning electron microscopy, micro-Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectrometry. The analysis of the growth process indicates that hydrogen can improve the formation of MoSe2 nanoflakes and significantly alter their properties due to the high reduction capacity of hydrogen and the creation of more nucleation centers of MoSe2 nanoflakes on the silicon surface. The study of photoluminescent (PL) properties reveals that the MoSe2 nanoflakes can generate a strong PL band at about 631 nm, differently from the plain MoSe2 nanoflakes. The major difference in the PL properties may be related to the edges of MoSe2 nanoflakes. These results can be used to control the growth and structure of MoSe2-based nanomaterials and contribute to the development of advanced MoSe2-based optoelectronic devices.

  20. Study of the influence of the temperature in the magnetic properties and in microstructure in the permanent magnets Pr-Fe-B-Nb-Co based obtained by hydrogen; Estudo da influencia da temperatura nas propriedades magneticas e na microestrutura nos imas permanentes a base de Pr-Fe-B-Nb-Co obtidos com hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Suelanny Carvalho da

    2007-07-01

    Fine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900 deg C with the purpose of optimizing the HDDR treatment for Pr{sub 14}Fe{sub 80}B{sub 6} and Pr{sub 14}Fe{sub bal}Co{sub x}B{sub 6}Nb{sub 0,1} (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100 deg C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880 deg C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840 deg C and 820 deg C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840 deg C. The optimum desorption temperature for achieving high anisotropy for Pr{sub 14}Fe{sub 80}B{sub 6} and Pr{sub 14}Fe{sub 79,9}B{sub 6}Nb{sub 0,1} was 820 deg C. The best remanence (862 mT) was achieved with the Pr{sub 14}Fe{sub 67,9}B{sub 6}Co{sub 12}Nb{sub 0,1} magnet, processed at 840 deg C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr{sub 14}Fe{sub 80}B{sub 6} HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy has also been employed to reveal the morphology of the HDDR powder. (author)

  1. Effect of an external electric field on the dissociation energy and the electron density properties: The case of the hydrogen bonded dimer HF⋯HFa)

    Science.gov (United States)

    Mata, Ignasi; Molins, Elies; Alkorta, Ibon; Espinosa, Enrique

    2009-01-01

    The effect of a homogeneous external electric field parallel to the hydrogen bond in the FH⋯FH dimer has been studied by theoretical methods. The quantum theory of atoms in molecules methodology has been used for analyzing the electron distribution of the dimer, calculated with different hydrogen bond distances and external field magnitudes. It is shown that an electric field in the opposite direction to the dipole moment of the system strengthens the interaction due to a larger mutual polarization between both molecules and increases the covalent character of the hydrogen bond, while an external field in the opposite direction has the inverse effect. The properties of the complex at its equilibrium geometry with applied field have been calculated, showing that dependencies between hydrogen bond distance, dissociation energy, and properties derived from the topological analysis of the electron distribution are analogous to those observed in families of XDH⋯AY complexes. The application of an external field appears as a useful tool for studying the effect of the atomic environment on the hydrogen bond interaction. In the case of FH⋯FH, both the kinetic energy density and the curvature of the electron density along the hydrogen bond at the bond critical point present a surprisingly good linear dependence on the dissociation energy. The interaction energy can be modeled by the sum of two exponential terms that depend on both the hydrogen bond distance and the applied electric field. Moreover, as indicated by the resulting interaction energy observed upon application of different external fields, the equilibrium distance varies linearly with the external field, and the dependence of the dissociation energy on either the hydrogen bond distance or the external electric field is demonstrated to be exponential.

  2. Hydrogen retention in tungsten materials studied by Laser Induced Desorption

    NARCIS (Netherlands)

    Zlobinski, M.; Philipps, V.; Schweer, B.; Huber, A.; M. Reinhart,; Möller, S.; Sergienko, G.; Samm, U.; Hoen, M. H. J. 't; Manhard, A.; Schmid, K.

    2013-01-01

    Development of methods to characterise the first wall in ITER and future fusion devices without removal of wall tiles is important to support safety assessments for tritium retention and dust production and to understand plasma wall processes in general. Laser based techniques are presently under

  3. Internal friction and gas desorption of {C}/{C} composites

    Science.gov (United States)

    Serizawa, H.; Sato, S.; Kohyama, A.

    1994-09-01

    {C}/{C} composites are the most promising candidates as high heat flux component materials, where temperature dependence of mechanical properties and gas desorption behavior at elevated temperature are important properties. At the beginning, the newly developed internal friction measurement apparatus, which enables the accurate measurement of dynamic elastic properties up to 1373 K along with the measurement of gas desorption behavior, was used. The materials studied were unidirectional (UD) {C}/{C} composites reinforced with mesophase pitch-based carbon fibers, which were heat treated at temperatures ranging from 1473 to 2773 K which produced a variety of graphitized microstructures. Two-dimensional (2D) {C}/{C} composites reinfored with flat woven fabrics of PAN type carbon fibers were also studied. These materials were heat treated at 1873 K. From the temperature spectrum of internal friction of 2D {C}/{C} composites, these internal friction peaks were detected and were related to gas desorption. Also the temperature dependence of Young's modulus of UD {C}/{C} composites, negative and positive dependence of Young's modulus were observed reflecting microstructure changes resulting from the heat treatments.

  4. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1991-01-01

    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  5. Film growth, adsorption and desorption kinetics of indigo on SiO2

    Science.gov (United States)

    Scherwitzl, Boris; Resel, Roland; Winkler, Adolf

    2014-05-01

    Organic dyes have recently been discovered as promising semiconducting materials, attributable to the formation of hydrogen bonds. In this work, the adsorption and desorption behavior, as well as thin film growth was studied in detail for indigo molecules on silicon dioxide with different substrate treatments. The material was evaporated onto the substrate by means of physical vapor deposition under ultra-high vacuum conditions and was subsequently studied by Thermal Desorption Spectroscopy (TDS), Auger Electron Spectroscopy, X-Ray Diffraction, and Atomic Force Microscopy. TDS revealed initially adsorbed molecules to be strongly bonded on a sputter cleaned surface. After further deposition a formation of dimers is suggested, which de-stabilizes the bonding mechanism to the substrate and leads to a weakly bonded adsorbate. The dimers are highly mobile on the surface until they get incorporated into energetically favourable three-dimensional islands in a dewetting process. The stronger bonding of molecules within those islands could be shown by a higher desorption temperature. On a carbon contaminated surface no strongly bonded molecules appeared initially, weakly bonded monomers rather rearrange into islands at a surface coverage that is equivalent to one third of a monolayer of flat-lying molecules. The sticking coefficient was found to be unity on both substrates. The desorption energies from carbon covered silicon dioxide calculated to 1.67 ± 0.05 eV for multilayer desorption from the islands and 0.84 ± 0.05 eV for monolayer desorption. Corresponding values for desorption from a sputter cleaned surface are 1.53 ± 0.05 eV for multilayer and 0.83 ± 0.05 eV for monolayer desorption.

  6. Film growth, adsorption and desorption kinetics of indigo on SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Scherwitzl, Boris, E-mail: b.scherwitzl@tugraz.at; Resel, Roland; Winkler, Adolf [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)

    2014-05-14

    Organic dyes have recently been discovered as promising semiconducting materials, attributable to the formation of hydrogen bonds. In this work, the adsorption and desorption behavior, as well as thin film growth was studied in detail for indigo molecules on silicon dioxide with different substrate treatments. The material was evaporated onto the substrate by means of physical vapor deposition under ultra-high vacuum conditions and was subsequently studied by Thermal Desorption Spectroscopy (TDS), Auger Electron Spectroscopy, X-Ray Diffraction, and Atomic Force Microscopy. TDS revealed initially adsorbed molecules to be strongly bonded on a sputter cleaned surface. After further deposition a formation of dimers is suggested, which de-stabilizes the bonding mechanism to the substrate and leads to a weakly bonded adsorbate. The dimers are highly mobile on the surface until they get incorporated into energetically favourable three-dimensional islands in a dewetting process. The stronger bonding of molecules within those islands could be shown by a higher desorption temperature. On a carbon contaminated surface no strongly bonded molecules appeared initially, weakly bonded monomers rather rearrange into islands at a surface coverage that is equivalent to one third of a monolayer of flat-lying molecules. The sticking coefficient was found to be unity on both substrates. The desorption energies from carbon covered silicon dioxide calculated to 1.67 ± 0.05 eV for multilayer desorption from the islands and 0.84 ± 0.05 eV for monolayer desorption. Corresponding values for desorption from a sputter cleaned surface are 1.53 ± 0.05 eV for multilayer and 0.83 ± 0.05 eV for monolayer desorption.

  7. Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

    Directory of Open Access Journals (Sweden)

    Sara J. Callori

    2016-05-01

    Full Text Available Due to hydrogen possessing a relatively large neutron scattering length, hydrogen absorption and desorption behaviors in metal thin films can straightforwardly be investigated by neutron reflectometry. However, to further elucidate the chemical structure of the hydrogen absorbing materials, complementary techniques such as high resolution X-ray reflectometry and diffraction remain important too. Examples of work on such systems include Nb- and Pd-based multilayers, where Nb and Pd both have strong affinity to hydrogen. W/Nb and Fe/Nb multilayers were measured in situ with unpolarized and polarized neutron reflectometry under hydrogen gas charging conditions. The gas-pressure/hydrogen-concentration dependence, the hydrogen-induced macroscopic film swelling as well as the increase in crystal lattice plane distances of the films were determined. Ferromagnetic-Co/Pd multilayers were studied with polarized neutron reflectometry and in situ ferromagnetic resonance measurements to understand the effect of hydrogen absorption on the magnetic properties of the system. This electronic effect enables a novel approach for hydrogen sensing using a magnetic readout scheme.

  8. Tunable preparation of ruthenium nanoparticles with superior size-dependent catalytic hydrogenation properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuan; Luo, Yaodong; Yang, Xuan; Yang, Yaxin; Song, Qijun, E-mail: qsong@jiangnan.edu.cn

    2017-06-15

    Highlights: • A facile and efficient strategy is firstly developed for the synthesis of Ru NPs. • Ru NPs are stable and uniform with the controllable sizes from 2.6 to 51.5 nm. • Ru NPs exhibit size-dependent and superior catalytic hydrogenation activity. - Abstract: Ruthenium (Ru) featured with an unusual catalytic behavior is of great significance in several heterogeneous and electro-catalytic reactions. The preparation of tractable Ru nanocatalysts and the building of highly active catalytic system at ambient temperature remains a grand challenge. Herein, a facile strategy is developed for the controllable preparation of Ru nanoparticles (NPs) with the sizes ranging from 2.6 to 51.5 nm. Ru NPs show superior size-dependent catalytic performance with the best kinetic rate constant as high as −1.52 min{sup −1}, which could far surpass the other traditional noble metals. Ru NPs exert exceedingly efficient low-temperature catalytic activity and good recyclability in the catalytic reduction of nitroaromatic compounds (NACs) and azo dyes. The developed catalytic system provides a distinguishing insight for the artificial preparation of Ru NPs with desired sizes, and allows for the development of rational design rules for exploring catalysts with superior catalytic performances, potentially broadening the applications of metallic NP-enabled catalytic analysis.

  9. How far can a single hydrogen bond tune the spectral properties of the GFP chromophore?

    DEFF Research Database (Denmark)

    Kiefer, Hjalte; Lattouf, Elie; Persen, Natascha Wardinghus

    2015-01-01

    Photoabsorption of the hydrogen-bonded complex of a neutral and an anionic Green Fluorescent Protein chromophore has been studied using a new dual-detection approach to action-absorption spectroscopy. Following absorption of one photon, dissociation through a single channel ensures that the full...... absorption spectrum is measured. Our theoretical account of the spectral shape reveals that the anionic 0–0 transition (464 nm) is blue-shifted compared to that of the wild-type protein (478 nm) due to the stronger H-bond in the dimer, and represents an upper bound for that of the isolated anion. At the same...... time, the apparent effect of the H-bond for the neutral chromophore is as large as 0.5 eV, red-shifting the absorption maximum of the isolated neutral (340 nm) to that measured in the dimer (393 nm) and various proteins ([similar]395 nm). This shift results from changes in the topography of potential...

  10. Fabrication variables affecting the structure and properties of supported carbon molecular sieve membranes for hydrogen separation

    KAUST Repository

    Briceño, Kelly

    2012-10-01

    A high molecular weight polyimide (Matrimid) was used as a precursor for fabricating supported carbon molecular sieve membranes without crack formation at 550-700°C pyrolysis temperature. A one-step polymer (polyimide) coating method as precursor of carbon layer was used without needing a prior modification of a TiO 2 macroporous support. The following fabrication variables were optimized and studied to determine their effect on the carbon structure: polymeric solution concentration, solvent extraction, heating rate and pyrolysis temperature. Two techniques (Thermogravimetric analysis and Raman spectroscopy) were used to determine these effects on final carbon structure. Likewise, the effect of the support was also reported as an additional and important variable in the design of supported carbon membranes. Atomic force microscopy and differential scanning calorimetry quantified the degree of influence. Pure gas permeation tests were performed using CH 4, CO, CO 2 and H 2. The presence of a molecular sieving mechanism was confirmed after defects were plugged with PDMS solution at 12wt%. Gas selectivities higher than Knudsen theoretical values were reached with membranes obtained over 650°C, showing as best values 4.46, 4.70 and 10.62 for H 2/N 2, H 2/CO and H 2/CH 4 ratio, respectively. Permeance values were over 9.82×10 -9mol/(m 2Pas)during pure hydrogen permeation tests. © 2012 Elsevier B.V.

  11. Tailoring the properties of ammine metal borohydrides for solid-state hydrogen storage.

    Science.gov (United States)

    Jepsen, Lars H; Ley, Morten B; Filinchuk, Yaroslav; Besenbacher, Flemming; Jensen, Torben R

    2015-04-24

    A series of halide-free ammine manganese borohydrides, Mn(BH4 )2 ⋅nNH3 , n=1, 2, 3, and 6, a new bimetallic compound Li2 Mn(BH4 )4 ⋅6NH3 , and the first ammine metal borohydride solid solution Mg1-x Mnx (BH4 )2 ⋅6NH3 are presented. Four new crystal structures have been determined by synchrotron radiation powder X-ray diffraction and the thermal decomposition is systematically investigated for all the new compounds. The solid-gas reaction between Mn(BH4 )2 and NH3 provides Mn(BH4 )2 ⋅6NH3 . The number of NH3 per Mn has been varied by mechanochemical treatment of Mn(BH4 )2 ⋅6NH3 -Mn(BH4 )2 mixtures giving rise to increased hydrogen purity for n/m≤1 for M(BH4 )m ⋅nNH3 . The structures of Mg(BH4 )2 ⋅3NH3 and Li2 Mg(BH4 )4 ⋅6NH3 have been revisited and new structural models are presented. Finally, we demonstrate that ammonia destabilizes metal borohydrides with low electronegativity of the metal (χp ∼1.6) are generally stabilized. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Scaling properties of adsorption energies for hydrogen-containing molecules on transition-metal surfaces

    DEFF Research Database (Denmark)

    Abild-Pedersen, Frank; Greeley, Jeffrey Philip; Studt, Felix

    2007-01-01

    Density functional theory calculations are presented for CHx, x=0,1,2,3, NHx, x=0,1,2, OHx, x=0,1, and SHx, x=0,1 adsorption on a range of close-packed and stepped transition-metal surfaces. We find that the adsorption energy of any of the molecules considered scales approximately with the adsorp......Density functional theory calculations are presented for CHx, x=0,1,2,3, NHx, x=0,1,2, OHx, x=0,1, and SHx, x=0,1 adsorption on a range of close-packed and stepped transition-metal surfaces. We find that the adsorption energy of any of the molecules considered scales approximately...... with the adsorption energy of the central, C, N, O, or S atom, the scaling constant depending only on x. A model is proposed to understand this behavior. The scaling model is developed into a general framework for estimating the reaction energies for hydrogenation and dehydrogenation reactions....

  13. Spiral Surface Growth without Desorption

    Energy Technology Data Exchange (ETDEWEB)

    Karma, A.; Plapp, M. [Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115 (United States)

    1998-11-01

    Spiral surface growth is well understood in the limit where the step motion is controlled by the local supersaturation of adatoms near the spiral ridge. In epitaxial thin-film growth, however, spirals can form in a step-flow regime where desorption of adatoms is negligible and the ridge dynamics is governed by the nonlocal diffusion field of adatoms on the whole surface. We investigate this limit numerically using a phase-field formulation of the Burton-Cabrera-Frank model, as well as analytically. Quantitative predictions, which differ strikingly from those of the local limit, are made for the selected step spacing as a function of the deposition flux, as well as for the dependence of the relaxation time to steady-state growth on the screw dislocation density. {copyright} {ital 1998} {ital The American Physical Society }

  14. Influence of hydrogenation on the structural and magnetic properties of compounds based on cerium and crystallizing in the tetragonal CeFeSi-type structure

    NARCIS (Netherlands)

    Chevalier, B.; Pasturel, M.; Bobet, J. L.; Isnard, O.

    2005-01-01

    The hydrogen absorption properties of CeMnGe, CeFeSi and CeCoX (X=Si and Ge) have been investigated. Neutron powder diffraction performed on deuteride CeCoGeD indicates that D-atoms are inserted in the pseudo-tetrahedral interstices [Ce

  15. Carbon nanotube materials for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J. [National Renewable Energy Lab., Golden, CO (United States)

    1998-08-01

    Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

  16. Gallium Arsenate Dihydrate under Pressure: Elastic Properties, Compression Mechanism, and Hydrogen Bonding.

    Science.gov (United States)

    Spencer, Elinor C; Soghomonian, Victoria; Ross, Nancy L

    2015-08-03

    Gallium arsenate dihydrate is a member of a class of isostructural compounds, with the general formula M(3+)AsO4·2H2O (M(3+) = Fe, Al, In, or Ga), which are being considered as potential solid-state storage media for the sequestration of toxic arsenic cations. We report the first high-pressure structural analysis of a metal arsenate dihydrate, namely, GaAsO4·2H2O. This compound crystallizes in the orthorhombic space group Pbca with Z = 8. Accurate unit cell parameters as a function of pressure were obtained by high-pressure single-crystal X-ray diffraction, and a bulk modulus of 51.1(3) GPa for GaAsO4·2H2O was determined from a third-order Birch-Murnaghan equation of state fit to the P-V data. Assessment of the pressure dependencies of the unit cell lengths showed that the compressibility of the structure along the axial directions increases in the order of [010] < [100] < [001]. This order was found to correlate well with the proposed compression mechanism for GaAsO4·2H2O, which involves deformation of the internal channel void spaces of the polyhedral helices that lie parallel to the [010] direction, and increased distortion of the GaO6 octahedra. The findings of the high-pressure diffraction experiment were further supported by the results from variable-pressure Raman analysis of GaAsO4·2H2O. Moreover, we propose a revised and more complex model for the hydrogen-bonding scheme in GaAsO4·2H2O, and on the basis of this revision, we reassigned the peaks in the OH stretching regions of previously published Raman spectra of this compound.

  17. Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Hayashi, Y.; Yu, G.; Rahman, M. M.; Krishna, K. M.; Soga, T.; Jimbo, T.; Umeno, M.

    2001-06-01

    Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH4 as the source of carbon and with different nitrogen flow rates (N2/CH4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron spin resonance (ESR), photoluminescence (PL) and spectroscopic ellipsometry (SE). Raman spectroscopy and IR absorption reveal an increase in sp2-bonded carbon or a change in sp2 domain size with increasing nitrogen flow rate. It is found that the configuration of nitrogen atoms incorporated into an amorphous carbon network gradually changes from nitrogen atoms surrounded by three (σ bonded) to two (π bonded) neighboring carbons with increasing nitrogen flow rate. Tauc optical gap is reduced from 2.6 to 2.0 eV, and the ESR spin density and the peak-to-peak linewidth increase sharply with increasing nitrogen flow rate. Excellent agreement has been found between the measured SE data and modeled spectra, in which an empirical dielectric function of amorphous materials and a linear void distribution along the thickness have been assumed. The influence of nitrogen on the electronic density of states is explained based on the optical properties measured by UV-VIS and PL including nitrogen lone pair band.

  18. Spatial Variations of Turbulent Properties of Neutral Hydrogen Gas in the Small Magellanic Cloud Using Structure-function Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nestingen-Palm, David; Stanimirović, Snežana; González-Casanova, Diego F.; Babler, Brian [Astronomy Department, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706-1582 (United States); Jameson, Katherine; Bolatto, Alberto, E-mail: sstanimi@astro.wisc.edu [Astronomy Department and Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742 (United States)

    2017-08-10

    We investigate spatial variations of turbulent properties in the Small Magellanic Cloud (SMC) by using neutral hydrogen (H i) observations. With the goal of testing the importance of stellar feedback on H i turbulence, we define central and outer SMC regions based on the star formation rate (SFR) surface density, as well as the H i integrated intensity. We use the structure function and the velocity channel analysis to calculate the power-law index ( γ ) for both underlying density and velocity fields in these regions. In all cases, our results show essentially no difference in γ between the central and outer regions. This suggests that H i turbulent properties are surprisingly homogeneous across the SMC when probed at a resolution of 30 pc. Contrary to recent suggestions from numerical simulations, we do not find a significant change in γ due to stellar feedback as traced by the SFR surface density. This could be due to the stellar feedback being widespread over the whole of the SMC, but more likely due to a large-scale gravitational driving of turbulence. We show that the lack of difference between central and outer SMC regions cannot be explained by the high optical depth H I.

  19. Influence of Conditions of Pd/SnO2 Nanomaterial Formation on Properties of Hydrogen Sensors

    Science.gov (United States)

    Sokovykh, E. V.; Oleksenko, L. P.; Maksymovych, N. P.; Matushko, I. P.

    2017-06-01

    Metal oxide sensors were created using nanosized tin dioxide obtained by a sol-gel method. Gas-sensitive layers of the sensors were impregnated with PdCl2 solutions of different concentrations to increase sensitivities of the proposed sensors. Influence of different temperature conditions of the sensor formation on the sensor properties was studied. It was found that decreasing duration of high-temperature sensor treatment prevents enlargement of particles of the gas-sensitive materials. It was shown that the sensors based on materials with smaller particle sizes showed higher sensor responses to 40 ppm H2. Obtained results were explained in terms of substantial influence of length of the common boundaries between the material particles of tin dioxide and palladium on the gas-sensitive properties of the sensors. The obtained sensors had possessed a fast response and recovery time and demonstrated stable characteristics during their long-term operation.

  20. Hydrogen-bond vibrational and energetic dynamical properties in sI and sII clathrate hydrates and in ice Ih: Molecular dynamics insights

    Science.gov (United States)

    Chakraborty, Somendra Nath; English, Niall J.

    2015-10-01

    Equilibrium molecular dynamics (MD) simulations have been performed on cubic (sI and sII) polymorphs of methane hydrate, and hexagonal ice (ice Ih), to study the dynamical properties of hydrogen-bond vibrations and hydrogen-bond self-energy. It was found that hydrogen-bond energies are greatest in magnitude in sI hydrates, followed by sII, and their energies are least in magnitude in ice Ih. This is consistent with recent MD-based findings on thermal conductivities for these various materials [N. J. English and J. S. Tse, Phys. Rev. Lett. 103, 015901 (2009)], in which the lower thermal conductivity of sI methane hydrate was rationalised in terms of more strained hydrogen-bond arrangements. Further, modes for vibration and energy-transfer via hydrogen bonds in sI hydrate were found to occur at higher frequencies vis-à-vis ice Ih and sII hydrate in both the water-librational and OH⋯H regions because of the more strained nature of hydrogen bonds therein.

  1. Hydrogen in carbon foils made by DC glow discharge in ethylene

    Science.gov (United States)

    Bailey, P.; Armour, D. G.; England, J. B. A.; Tait, N. R. S.; Tolfree, D. W. L.

    1983-08-01

    Thermal desorption has been studied from thin films of carbon prepared by dc glow discharge in ethylene. The only gases released in significant quantities are hydrogen and methane. Both releases can be characterised by a continuum of activation energies but the methane release peaks at a lower temperature than that from hydrogen. The estimated total hydrogen release is compared with the hydrogen content determined by nuclear scattering experiments. Infra red studies suggest that the majority of CH 2 and CH 3 bonds can be ruptured by annealing at 300°C, a temperature well below the hydrogen and methane release rate maxima. Possible hydrogen bonding modes and desorption mechanisms are discussed.

  2. The effect of structural and energetic parameters of MOFs and COFs towards the improvement of their hydrogen storage properties.

    Science.gov (United States)

    Tylianakis, Emmanuel; Klontzas, Emmanouel; Froudakis, George E

    2009-05-20

    Open-framework materials have been proposed as potential materials for hydrogen storage. Metal-organic framework (MOF) and covalent-organic framework (COF) materials are under extensive study to discover their storage abilities. In particular the IRMOF family of materials have been considered as ideal to study the effect of different factors that affect the hydrogen storage capacity. In this paper, we analyse the effect of different factors such as surface area, pore volume and the interaction of hydrogen with the molecular framework on the hydrogen uptake of such materials. Through this analysis we propose guidelines to enhance hydrogen storage capacity of already synthesized materials and recommend advanced materials for this application.

  3. Thermodynamic properties and theoretical rocket performance of hydrogen to 100,000 K and 1.01325 x 10 to the 8th power N/sq m

    Science.gov (United States)

    Patch, R. W.

    1971-01-01

    The composition and thermodynamic properties were calculated for 100 to 110,000 K and 1.01325 x 10 to the 2nd power to 1.01325 x 10 to the 8th power N/sq m for chemical equilibrium in the Debye-Huckel and ideal-gas approximations. Quantities obtained were the concentrations of hydrogen atoms, protons, free electrons, hydrogen molecules, negative hydrogen ions, hydrogen diatomic molecular ions, and hydrogen triatomic molecular ions, and the enthalpy, entropy, average molecular weight, specific heat at constant pressure, density, and isentropic exponent. Electronically excited states of H and H2 were included. Choked, isentropic, one-dimensional nozzle flow with shifting chemical equilibrium was calculated to the Debye-Huckel and ideal-gas approximations for stagnation temperatures from 2500 to 100,000 K. The mass flow per unit throat area and the sonic flow factor were obtained. The pressure ratio, temperature, velocity, and ideal and vacuum specific impulses at the throat and for pressure ratios as low as 0.000001 downstream were found. For high temperatures at pressures approaching 1.01325 x 10 to the 8th power N/sq m, the ideal-gas approximation was found to be inadequate for calculations of composition, precise thermodynamic properties, and precise nozzle flow. The greatest discrepancy in nozzle flow occurred in the exit temperature, which was as much as 21 percent higher when the Debye-Huckel approximation was used.

  4. Reduced Graphene Oxide Coating with Anticorrosion and Electrochemical Property-Enhancing Effects Applied in Hydrogen Storage System.

    Science.gov (United States)

    Du, Yi; Li, Na; Zhang, Tong-Ling; Feng, Qing-Ping; Du, Qian; Wu, Xing-Hua; Huang, Gui-Wen

    2017-08-30

    Low-capacity retention is the most prominent problem of the magnesium nickel alloy (Mg2Ni), which prevents it from being commercially applied. Here, we propose a practical method for enhancing the cycle stability of the Mg2Ni alloy. Reduced graphene oxide (rGO) possesses a graphene-based structure, which could provide high-quality barriers that block the hydroxyl in the aqueous electrolyte; it also possesses good hydrophilicity. rGO has been successfully coated on the amorphous-structured Mg2Ni alloy via electrostatic assembly to form the rGO-encapsulated Mg2Ni alloy composite (rGO/Mg2Ni). The experimental results show that ζ potentials of rGO and the modified Mg2Ni alloy are totally opposite in water, with values of -11.0 and +22.4 mV, respectively. The crumpled structure of rGO sheets and the contents of the carbon element on the surface of the alloy are measured using scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometry. The Tafel polarization test indicates that the rGO/Mg2Ni system exhibits a much higher anticorrosion ability against the alkaline solution during charging/discharging. As a result, high-capacity retentions of 94% (557 mAh g(-1)) at the 10th cycle and 60% (358 mAh g(-1)) at the 50th cycle have been achieved, which are much higher than the results on Mg2Ni capacity retention combined with the absolute value reported so far to our knowledge. In addition, both the charge-transfer reaction rate and the hydrogen diffusion rate are proven to be boosted with the rGO encapsulation. Overall, this work demonstrates the effective anticorrosion and electrochemical property-enhancing effects of rGO coating and shows its applicability in the Mg-based hydrogen storage system.

  5. Hydrogen absorption and lithium ion conductivity in Li{sub 6}NBr{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Howard, M.A. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Clemens, O. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Technical University of Darmstadt, Joint Research Laboratory Nanomaterials, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Slater, P.R. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Anderson, P.A., E-mail: p.a.anderson@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • Li{sub 6}NBr{sub 3} was synthesized via solid state methods and hydrogenation attempted. • Hydrogenation of a lithium nitride halide was demonstrated for the first time. • Powder XRD and Raman spectroscopy showed that hydrogenation had gone to completion. • The ionic conductivities of Li{sub 6}NBr{sub 3} and Li{sub 3}N were compared through A.C. impedance spectroscopy. • The lower conductivity of Li{sub 6}NBr{sub 3} is consistent with its higher hydrogenation temperature. - Abstract: The reaction of lithium amide and imide with lithium halides to form new amide halide or imide halide phases has led to improved hydrogen desorption and absorption properties and, for the amides, lithium ion conductivities. Here we investigate the effect of bromide incorporation on the ionic conductivity and hydrogen absorption properties of lithium nitride. For the first time we show that it is possible for a lithium halide nitride, the cubic bromide nitride Li{sub 6}NBr{sub 3}, to take up hydrogen—a necessary condition for potential use as a reversible solid-state hydrogen storage material. Powder X-ray diffraction showed the formation of Li{sub 2}Br(NH{sub 2}) and LiBr, and Raman spectroscopy confirmed that only amide anions were present and that the hydrogen uptake reaction had gone to completion. The lithium ion conductivity of Li{sub 6}NBr{sub 3} at the hydrogenation temperature was found to be less than that of Li{sub 3}N, which may be a significant factor in the kinetics of the hydrogenation process.

  6. Nonisothermal Desorption of the Libr Aqueous Salt Solution in Minichannels

    Directory of Open Access Journals (Sweden)

    Misyura S.Y.

    2015-01-01

    Full Text Available This work is devoted the research for two (three-phase flows of LiBr water solution in minichannels with different heat flux and wall thicknesses. Six flow patterns have been observed: a bubble flow, plug flow, laminar and oscillating laminar flow, mist flow, and flow locking. The physical solution properties and the equilibrium conditions change in time. The desorption rate depends not only on the heat flow and speed ratio of vapor to liquid, but also on the total area of the interface (liquid-vapor. The third phase (solid crystal hydrates are formed under high heat fluxes and in the presence of boiling crisis. A variation in the wall thickness leads to a change in the desorption mode. With increasing wall thickness the boiling crisis is realized at higher heat fluxes.

  7. Realizing nanographene activated by a vacancy to solve hydrogen storage problem

    Science.gov (United States)

    Sunnardianto, Gagus Ketut; Maruyama, Isao; Kusakabe, Koichi

    We found a triply hydrogenated vacancy (V111) in nanographene reduces an activation barrier of adsorption-desorption process in both ways in an equal manner from the known values for pristine graphene as well as those of other hydrogenated vacancies of graphene. This finding may give a key to overcome existing problems in the hydrogen uptake and release processes in known hydrogen storage materials, e.g. graphene and organic hydrides (OHs) in near ambient operation temperature. In this study, we used DFT-NEB simulation to estimate the barrier height, which is supported by realized real experiments. We consider a nanographene molecule (VANG) which contains V111 with armchair structure at the periphery. We found interesting feature in comparable values of energy barriers for both hydrogen uptake and release, where hydrogenation process is even a little bit endothermic and dehydrogenation is a little but exothermic nature. Thus, this material structure acts as ``self-catalytic properties'', which has an important role in reducing an energy barrier and as a trapping site for hydrogen serving a new material prevailing other hopeful candidates. The work is supported by JSPS KAKENHI in Science of Atomic Layers\\x9D.

  8. Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

    Science.gov (United States)

    Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

    2016-12-20

    Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

  9. Thermodynamic Property Study of Nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H Systems by High Pressure DSC Method

    OpenAIRE

    Huaiyu Shao; Gongbiao Xin; Xingguo Li; Etsuo Akiba

    2013-01-01

    Mg, Ni, and Cu nanoparticles were synthesized by hydrogen plasma metal reaction method. Preparation of Mg2Ni and Mg2Cu alloys from these Mg, Ni, and Cu nanoparticles has been successfully achieved in convenient conditions. High pressure differential scanning calorimetry (DSC) technique in hydrogen atmosphere was applied to study the synthesis and thermodynamic properties of the hydrogen absorption/desorption processes of nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H systems. Van’t Hoff equation o...

  10. Hydrogen-Trapping Mechanisms in Nanostructured Steels

    Science.gov (United States)

    Szost, B. A.; Vegter, R. H.; Rivera-Díaz-del-Castillo, Pedro E. J.

    2013-10-01

    Nanoprecipitation-hardened martensitic bearing steels (100Cr6) and carbide-free nanobainitic steels (superbainite) are examined. The nature of the hydrogen traps present in both is determined via the melt extraction and thermal desorption analysis techniques. It is demonstrated that 100Cr6 can admit large amounts of hydrogen, which is loosely bound to dislocations around room temperature; however, with the precipitation of fine coherent vanadium carbide traps, hydrogen can be immobilized. In the case of carbide-free nanostructured bainite, retained austenite/bainite interfaces act as hydrogen traps, while concomitantly retained austenite limits hydrogen absorption. In nanostructured steels where active hydrogen traps are present, it is shown that the total hydrogen absorbed is proportional to the trapped hydrogen, indicating that melt extraction may be employed to quantify trapping capacity.

  11. Transport properties of hydrogen passivated silicon nanotubes and silicon nanotube field effect transistors

    KAUST Repository

    Montes Muñoz, Enrique

    2017-01-24

    We investigate the electronic transport properties of silicon nanotubes attached to metallic electrodes from first principles, using density functional theory and the non-equilibrium Green\\'s function method. The influence of the surface termination is studied as well as the dependence of the transport characteristics on the chirality, diameter, and length. Strong electronic coupling between nanotubes and electrodes is found to be a general feature that results in low contact resistance. The conductance in the tunneling regime is discussed in terms of the complex band structure. Silicon nanotube field effect transistors are simulated by applying a uniform potential gate. Our results demonstrate very high values of transconductance, outperforming the best commercial silicon field effect transistors, combined with low values of sub-threshold swing.

  12. Electrical Characterization and Hydrogen Peroxide Sensing Properties of Gold/Nafion:Polypyrrole/MWCNTs Electrochemical Devices

    Science.gov (United States)

    Scandurra, Graziella; Arena, Antonella; Ciofi, Carmine; Saitta, Gaetano

    2013-01-01

    Electrochemical devices using as substrates copier grade transparency sheets are developed by using ion conducting Nafion: polypyrrole mixtures, deposited between gold bottom electrodes and upper electrodes based on Multi Walled Carbon Nanotubes (MWCNTs). The electrical properties of the Nafion:polypyrrole blends and of the gold/Nafion:polypyrrole/MWCNTs devices are investigated under dry conditions and in deionized water by means of frequency dependent impedance measurements and time domain electrical characterization. According to current-voltage measurements carried out in deionized water, the steady state current forms cycles characterized by redox peaks, the intensity and position of which reversibly change in response to H2O2, with a lower detection limit in the micromolar range. The sensitivity that is obtained is comparable with that of other electrochemical sensors that however, unlike our devices, require supporting electrolytes. PMID:23529125

  13. Investigation of thermal and optical properties of some quartet mixed hydrogen-bonded liquid crystals

    Science.gov (United States)

    Okumuş, Mustafa

    2017-11-01

    In this study, the thermal and optical properties of quartet mixtures formed at different weight ratios (1:1:1:1 and 1.5:1:1:1) from liquid crystals 4-octyloxy-4‧-cyanobiphenyl (8OCB), 4-hexylbenzoic acid, 4-(octyloxy)benzoic acid and 4-(decyloxy)benzoic acid were investigated by differential scanning calorimeter (DSC) and polarized optic microscopy (POM). The phase transition temperatures of the novel quartet mixtures measured in the DSC experiments are in line with the POM experiments. The experimental results clearly show that the novel liquid crystal mixtures have displayed pure liquid crystalline properties. According to the phase diagram drawn from DSC results, the nematic range of the novel mixture at the eutectic point is larger than the nematic ranges of the components. The mesomorphic structures of produced homolog complex mixtures are found to be smectic and nematic phases. But the smectic phase cannot be observed in the novel complex 1.5:1:1:1 mixture during continuous cooling. The nematic range of the novel complex 1.5:1:1:1 mixture is bigger than the nematic range of the novel complex 1:1:1:1 mixture with increasing 8OCB. Also, the nematic-to-isotropic phase transition temperature decreases with increasing the weight ratio of 8OCB in the complex quartet mixture. Another interesting result is that the produced mixtures are to be like a medical cream at room temperatures. Furthermore, order parameter and thermal stability factor of the transitions are also calculated.

  14. Reversible hydrogen storage by NaAlH4 confined within a titanium-functionalized MOF-74(Mg) nanoreactor.

    Science.gov (United States)

    Stavila, Vitalie; Bhakta, Raghunandan K; Alam, Todd M; Majzoub, Eric H; Allendorf, Mark D

    2012-11-27

    We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a "nanoreactor". Confining NaAlH(4) within these pores alters the decomposition pathway by eliminating the stable intermediate Na(3)AlH(6) phase observed during bulk decomposition and proceeding directly to NaH, Al, and H(2), in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH(4)@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH(4). However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H(2) desorption is reduced from 79.5 kJ mol(-1) in bulk Ti-doped NaAlH(4) to 57.4 kJ mol(-1) for nanoconfined NaAlH(4). The structural properties of nano-NaAlH(4)@MOF-74(Mg) were probed using (23)Na and (27)Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH(4)(-) anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage.

  15. Solvent-Assisted Desorption of 2,5-Lutidine from Polyurethane Films.

    Science.gov (United States)

    Boyne, Devon A; Varady, Mark J; Lambeth, Robert H; Eikenberg, Janlyn H; Bringuier, Stefan A; Pearl, Thomas P; Mantooth, Brent A

    2018-02-08

    A fundamental understanding of chemical interactions and transport mechanisms that result from introducing multiple chemical species into a polymer plays a key role in the development and optimization of membranes, coatings, and decontamination formulations. In this study, we explore the solvent-assisted desorption of a penetrant (2,5-lutidine) in polyurethane with aprotic (acetonitrile) and protic (methanol) solvents. Chemical interactions between solvent, penetrant, and polymer functional groups are characterized via time-resolved Fourier transform infrared spectroscopy (FTIR) during single and multicomponent exposures. For both solvents, an increase in the extraction rate of the penetrant is observed when the solvent is applied during desorption. Inspection of the FTIR spectra reveals two potential mechanisms that facilitate the enhanced desorption rate: (1) penetrant/solvent competition for hydrogen donor groups on the polymer backbone and (2) disruption of the self-interaction (cohesive forces) between neighboring polymer chains. Finally, the aprotic solvent is found to generate an order of magnitude greater desorption rate of the penetrant, which is attributed to a greater disruption of the self-interaction during penetrant desorption compared to the protic solvent and the inability of an aprotic solvent to form larger and potentially slower penetrant-solvent complexes.

  16. Conformational properties of oxazole-amino acids: effect of the intramolecular N-H···N hydrogen bond.

    Science.gov (United States)

    Siodłak, Dawid; Staś, Monika; Broda, Małgorzata A; Bujak, Maciej; Lis, Tadeusz

    2014-03-06

    Oxazole ring occurs in numerous natural peptides, but conformational properties of the amino acid residue containing the oxazole ring in place of the C-terminal amide bond are poorly recognized. A series of model compounds constituted by the oxazole-amino acids occurring in nature, that is, oxazole-alanine (L-Ala-Ozl), oxazole-dehydroalanine (ΔAla-Ozl), and oxazole-dehydrobutyrine ((Z)-ΔAbu-Ozl), was investigated using theoretical calculations supported by FTIR and NMR spectra and single-crystal X-ray diffraction. It was found that the main feature of the studied oxazole-amino acids is the stable conformation β2 with the torsion angles φ and ψ of -150°, -10° for L-Ala-Ozl, -180°, 0° for ΔAla-Ozl, and -120°, 0° for (Z)-ΔAbu-Ozl, respectively. The conformation β2 is stabilized by the intramolecular N-H···N hydrogen bond and predominates in the low polar environment. In the case of the oxazole-dehydroamino acids, the π-electron conjugation that is spread on the oxazole ring and C(α)═C(β) double bond is an additional stabilizing interaction. The tendency to adopt the conformation β2 clearly decreases with increasing the polarity of environment, but still the oxazole-dehydroamino acids are considered to be more rigid and resistant to conformational changes.

  17. Thermomechanical properties of zirconium tungstate/hydrogenated nitrile butadiene rubber (HNBR) composites for low-temperature applications

    Science.gov (United States)

    Akulichev, Anton G.; Alcock, Ben; Tiwari, Avinash; Echtermeyer, Andreas T.

    2016-12-01

    Rubber compounds for pressure sealing application typically have inferior dimensional stability with temperature fluctuations compared with their steel counterparts. This effect may result in seal leakage failures when subjected to decreases in temperature. Composites of hydrogenated nitrile butadiene rubber (HNBR) and zirconium tungstate as a negative thermal expansion filler were prepared in order to control the thermal expansivity of the material. The amount of zirconium tungstate (ZrW2O8) was varied in the range of 0 to about 40 vol%. The coefficient of thermal expansion (CTE), bulk modulus, uniaxial extension and compression set properties were measured. The CTE of the ZrW2O8-filled HNBR decreases with the filler content and it is reduced by a factor of 2 at the highest filler concentration used. The filler effect on CTE is found to be stronger when HNBR is below the glass transition temperature. The experimental thermal expansion data of the composites are compared with the theoretical estimates and predictions given by FEA. The effect of ZrW2O8 on the mechanical characteristics and compression set of these materials is also discussed.

  18. Adsorption and Desorption of Nitrogen and Water Vapor by clay

    Science.gov (United States)

    Cui, Deshan; Chen, Qiong; Xiang, Wei; Huang, Wei

    2015-04-01

    Adsorption and desorption of nitrogen and water vapor by clay has a significant impact on unsaturated soil physical and mechanical properties. In order to study the adsorption and desorption characteristics of nitrogen and water vapor by montmorillonite, kaolin and sliding zone soils, the Autosorb-iQ specific surface area and pore size analyzer instrument of United State was taken to carry out the analysis test. The adsorption and desorption of nitrogen at 77K and water vapor at 293K on clay sample were conducted. The theories of BET, FHH and hydration energy were taken to calculate the specific surface, surface fractal dimension and adsorption energy. The results show that the calculated specific surface of water vapor by clay is bigger than nitrogen adsorption test because clay can adsorb more water vapor molecule than nitrogen. Smaller and polar water vapor molecule can access the micropore and then adsorb on the mineral surface and mineral intralayer, which make the mineral surface cations hydrate and the mineral surface smoother. Bigger and nonpolar nitrogen molecule can not enter into the micropore as water vapor molecule and has weak interaction with clay surface.

  19. Hydrogen Trapping in Quenched and Tempered 0.42C-0.30Ti Steel Containing Bimodally Dispersed TiC Particles

    National Research Council Canada - National Science Library

    Wei, Fu-Gao; Hara, Toru; Tsuchida, Takehiro; Tsuzaki, Kaneaki

    2003-01-01

    The effect of tempering on hydrogen trapping in 0.42C-0.30Ti steel was studied by means of a hardness test, hydrogen thermal desorption spectrometry and high resolution transmission electron microscopy...

  20. Synthesis, structure, spectral properties and DFT quantum chemical calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen bonding on photoisomerization

    Science.gov (United States)

    Georgiev, Anton; Bubev, Emil; Dimov, Deyan; Yancheva, Denitsa; Zhivkov, Ivaylo; Krajčovič, Jozef; Vala, Martin; Weiter, Martin; Machkova, Maria

    2017-03-01

    In this paper three different "push-pull" 4-aminoazobenzene dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6-31 + G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in CHCl3 and DMF. The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered hydrogen bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔEtrans → cis, Δμtrans → cis, ΔHtrans → cis, ΔGtrans → cis and ΔStrans → cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in CHCl3 (nonpolar), EtOH (polar protic) and DMF (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents CHCl3 (nonpolar) and DMF (polar aprotic) by UV light irradiation with λ = 365 nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in CHCl3 and DMF. The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped

  1. Synthesis, structure, spectral properties and DFT quantum chemical calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen bonding on photoisomerization.

    Science.gov (United States)

    Georgiev, Anton; Bubev, Emil; Dimov, Deyan; Yancheva, Denitsa; Zhivkov, Ivaylo; Krajčovič, Jozef; Vala, Martin; Weiter, Martin; Machkova, Maria

    2017-03-15

    In this paper three different "push-pull" 4-aminoazobenzene dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6-31+G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in CHCl3 and DMF. The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered hydrogen bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔEtrans→cis, Δμtrans→cis, ΔHtrans→cis, ΔGtrans→cis and ΔStrans→cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in CHCl3 (nonpolar), EtOH (polar protic) and DMF (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents CHCl3 (nonpolar) and DMF (polar aprotic) by UV light irradiation with λ=365nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in CHCl3 and DMF. The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped electron

  2. Thermal desorption spectroscopy of palladium and copper on silica

    Science.gov (United States)

    Pierce, Daniel E.; Burns, Richard P.; Gabriel, Kenneth A.

    Thermal desorption spectroscopy of palladium and copper films grown on clean silica substrates was performed using CO2 laser heating. After cleaning the surface by high temperature heating, a controlled, low coverage dose of metal atoms was deposited on the substrate. Temperature ramping was achieved using a constant laser power, the value of which depended on the nature of the metal and substrate as well as the substrate size. At high temperatures (above 1025 K for palladium and above 975 K for copper), metal films vaporize and desorption spectra provide information about the nature of the metal deposit and metal-support interaction. With increasing coverage of palladium on silica, a positive temperature shift in the leading edge of desorption was seen. At higher coverages, above about 2 x 10(exp 15) atoms/sq cm, a common leading edge appears and zero-order kinetic analysis gave E(sub act) values between 3.9 and 4.3 +/- 0.1 eV which can be compared with the value of 3.83 eV for Delta (H(sub vap)) (1200 K) for palladium metal. Similar coverage-dependent properties were not seen for copper on silica; instead, a common desorption leading edge appeared down to submonolayer coverages. Zero-order analysis at about 1 x 10(exp 15) atoms/sq cm gave an E(sub act) of 3.3 +/- 0.1 eV, which is comparable with the value of 3.44 eV for Delta (H(sub vap)) (1100 K) for copper metal.

  3. The defect passivation effect of hydrogen on the optical properties of solution-grown ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Urgessa, Z.N., E-mail: zelalem.urgessa@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Mbulanga, C.M.; Tankio Djiokap, S.R.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Duvenhage, M.M.; Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300 (South Africa)

    2016-01-01

    In this study the effect of annealing environment on both low temperature and room temperature photoluminescence (PL) characteristics of ZnO nanorods, grown in solution, is presented. Particular attention is given to the effect of hydrogen defect passivation and its PL related line. It is shown that, irrespective of annealing ambient, an optimum annealing temperature of 300 °C suppresses the defect related emission and significantly improves the UV emission. By considering the stability of hydrogen impurities, the observed results in the PL spectra are analyzed. There is an observed asymmetric broadening on the low energy side of the bound exciton luminescence in the low temperature annealed samples which is explained by a high concentration of ionized impurities related to hydrogen. This has been attributed primarily to the conversion of hydrogen molecule to substitutional hydrogen on the oxygen site (H{sub O}) as a result of annealing.

  4. The effects of dynamic structural transformations on hydrogenation properties of Mg and MgNi thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pranevicius, L. [Vytautas Magnus University, 8 Vileikos St., LT-44404 Kaunas (Lithuania); Milcius, D. [Lithuanian Energy Institute, 3 Breslaujos St., LT-44403 Kaunas (Lithuania); Templier, C. [Universite de Poitiers, SP2MI, Teleport 2, Bd Marie et Pierre Curie BP 30179, Futuroscope (France)

    2009-06-15

    Mg capped with Al and Ti thin layers and Mg{sub x}Ni films have been sputter-deposited on quartz substrates and hydrogenated at 600 kPa for 250 C. A complete fast transformation of metallic into hydride phase is registered for the films, demonstrating the dynamic state of the internal microstructure under hydrogenation. It leads to local and long-range restructuring and the fast hydrogenation rate is attributed to the fast hydrogen uptake and transport along columns and grain boundaries of nanocrystallites. A slow H-loading is observed when the dynamic structural relaxation processes are suppressed by internal and external inhomogeneities such as barrier layers on the surface, new phases in the bulk and impurities. A partial transformation of metallic into hydride phase is registered when the structural formations newly nucleated at the initial stages of hydrogenation suppress dynamic processes and prevent the H-uptake. (author)

  5. Isotopic tracing of hydrogen transport and trapping in nuclear materials

    Science.gov (United States)

    Chêne, Jacques; Martin, Frantz

    2017-06-01

    Some illustrations of the use of deuterium or tritium for isotopic tracing of hydrogen absorption, transport and trapping in nuclear materials are presented. Isotopic tracing of hydrogen has been shown to be successful for the determination of the boundaries conditions for hydrogen desorption or absorption in a material exposed to a hydrogen source. Also, the unique capabilities of isotopic tracing and related techniques to characterize H interactions with point defects and dislocations acting as moving traps has been demonstrated. Such transport mechanisms are considered to play a major role in some stress corrosion cracking and hydrogen embrittlement mechanisms. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  6. Effect of the deposition temperature and a hydrogen post-annealing treatment on the structural, electrical, and optical properties of Ga-doped ZnO films

    Science.gov (United States)

    Lee, Min-Jung; Lee, Tae-Il; Lim, Jinhyong; Bang, Jungsik; Lee, Woong; Lee, Taeyoon; Myoung, Jae-Min

    2009-09-01

    The combined effects of the deposition temperature and a hydrogen post-annealing treatment on the structural, electrical, and optical properties of Ga-doped ZnO (GZO) films were investigated as a potential substitute for indium tin oxide transparent conductive oxide (TCO). On the as-deposited films, increasing the deposition temperature initially improved the electrical properties, but a deposition temperature in excess of 423 K resulted in the deterioration of the electrical properties due to the development of ZnGa2O4 and Ga2O3 phases originating from the excessive amount of the Ga dopant. While a post-annealing treatment of the GZO films in hydrogen leveled off the overall properties, improvement in the electrical property was observed only in films initially deposited at room temperature. This is attributed to the excessively high concentration of the dopant Ga released from ZnGa2O4 and Ga2O3 during the post-annealing treatment. It is therefore suggested that in the preparation of TCOs based on GZO films, the concentration of the dopant Ga should be carefully controlled to obtain the optimal properties by suppressing the formation of ZnGa2O4 and Ga2O3 that occurs due to the presence of excess Ga.

  7. The calculation of transport properties in quantum liquids using the maximum entropy numerical analytic continuation method: Application to liquid para-hydrogen

    OpenAIRE

    Rabani, Eran; Reichman, David R.; Krilov, Goran; Berne, Bruce J.

    2002-01-01

    We present a method based on augmenting an exact relation between a frequency-dependent diffusion constant and the imaginary time velocity autocorrelation function, combined with the maximum entropy numerical analytic continuation approach to study transport properties in quantum liquids. The method is applied to the case of liquid para-hydrogen at two thermodynamic state points: a liquid near the triple point and a high-temperature liquid. Good agreement for the self-diffusion constant and f...

  8. Mercaptosilane-assisted synthesis of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials and their enhanced hydrogenation properties.

    Science.gov (United States)

    Gao, Daowei; Zheng, Anmin; Zhang, Xin; Sun, Hui; Dai, Xiaoping; Yang, Ying; Wang, Hai; Qin, Yuchen; Xu, Shutao; Duan, Aijun

    2015-07-07

    A novel catalyst that consists of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials was synthesized. This catalyst exhibited high stability and a hierarchically porous structure of a micro-mesoporous composite and possessed a high density of active sites by confinement of sub-nanosized Pt particles within small-pore zeolites, showing high catalytic properties for the hydrogenation of 1,3-butadiene and cyclooctadiene at room temperature.

  9. Hydrogen adsorption on rhodium

    Energy Technology Data Exchange (ETDEWEB)

    Belyaeva, M.E.; Michri, A.A.; Kalish, T.V.; Pshenichnikov, A.G.; Kazarinov, V.E.

    1987-09-01

    Measurements of thermal desorption and electron work function were used to investigate the mechanism of hydrogen adsorption from the gas phase on rhodium single-crystal faces and on a polycrystalline rhodium sample at room temperatures over the pressure range from 1.3-10/sup -3/ to 1.3 x 10/sup -5/ Pa. It was found that dipoles oriented with their negative ends toward the gas phase (dipoles of type I) form more rapidly than dipoles having the opposite orientation (dipoles of type II). For formation of the latter, a mechanism is proposed according to which the rate-determining step of the overall process is the transition of reversibly adsorbed hydrogen to dipoles of type II (the spillover), which occurs at surface defects. It was shown that the kinetics of this process with respect to the individual defect obeys an equation which is zeroth order in theta/sub H/ and pressure.

  10. Investigation on hydrogenation performance of Mg{sub 2}Ni+10 wt.% NbN composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xin; Han, Shumin [Hebei Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhu, Yi [Inner Mongolia Rare Earth Ovonic Metal Hydride Co. Ltd., Baotou 014030 (China); Chen, Xiaocui; Ke, Dandan; Wang, Zhibin; Liu, Ting; Ma, Yufei [Hebei Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2015-01-15

    The Mg{sub 2}Ni+10 wt.% NbN composite was prepared by mechanical milling and its hydrogen absorption/desorption properties and microstructure were systematically investigated. XRD results indicated that NbN was stable during ball milling process while partly decomposed into NbN{sub 0.95} and NbH during hydriding/dehydriding cycles irreversibly. The composite exhibited excellent hydrogenation/dehydrogenation kinetics performance with 2.71 wt.% hydrogen absorbed in 60 s at 423 K and 0.81 wt.% hydrogen released in 2 h at 523 K, respectively. The H diffusion constant of the composite reached 14.98×10{sup −5} s{sup −1} which was more than twice increased than that of pure Mg{sub 2}Ni powder. The superior hydrogen storage properties of the composite were ascribed to the refined grain size and abundant N-defect points provided by NbN and NbN{sub 0.95} in the composite. - Graphical abstract: The Mg{sub 2}Ni+10 wt.% NbN composite displays improvements on particle size distribution as well as hydrogen storage properties compared with that of pure Mg{sub 2}Ni. - Highlights: • NbN is introduced into Mg{sub 2}Ni hydride by Ar protected ball-milling. • Surfaces of the additive NbN particle are reduced by Mg{sub 2}NiH{sub 4}. • Hydrogenation kinetic property at 423 K is double improved. • Dehydrogenation capacity at 523 K of composites is beyond double improved.

  11. Metal-loaded SBA-16-like silica – Correlation between basicity and affinity towards hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ouargli-Saker, R. [Department of Materials Engineering, University of Science and Technology, El M’naouer, BP 1505, Oran (Algeria); Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Bouazizi, N. [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Unité de recherche, Electrochimie, Matériaux et Environnement, Faculté des Sciences de Gabès, Université de Gabès, Cité Erriadh, 6072 Gabès (Tunisia); Boukoussa, B. [Department of Materials Engineering, University of Science and Technology, El M’naouer, BP 1505, Oran (Algeria); Lqamb, Laboratório de Química Analítica Ambiental, Faculdade de Química, Pontifícia Universidade Católica do Rio Grande do Sul (Brazil); Barrimo, Diana [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Paola-Nunes-Beltrao, Ana [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Laboratory of Materials Chemistry L.C.M, University of Oran1 Ahmed Ben Bella, BP 1524, El-Mnaouer, 31000 Oran (Algeria); Azzouz, A., E-mail: azzouz.a@uqam.ca [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada)

    2017-07-31

    Highlights: • Metal dispersion in longitudinal channels confers adsorption properties to SBA-16. • Both Fe{sup 0}-NPs and Cu{sup 0}-NPs seem to be responsible of this effect. • Effect of the repetitive adsorption-desorption cycles on CO{sub 2} and water sorption. • Hydrogen storage on the functionalized materials. - Abstract: Nanoparticles of Cu{sup o} (CuNPs) and Fe{sup o} (FeNPs) were dispersed in SBA-16-like silica, resulting metal-loaded materials (Cu-SBA-16 and Fe-SBA-16) with improved affinity towards hydrogen. Electron microscopy and X-ray diffraction showed that MNP dispersion occurs mainly inside SBA-16 channels. MNP incorporation was found to confer affinity to the silica surface, since higher CO{sub 2} retention capacity (CRC) was registered Cu/SBA-16 and Fe/SBA-16. This was accompanied by a significant improvement of the affinity towards hydrogen, as supported by hydrogen adsorption tests. This was explained in terms of strong hydrogen interaction with MNP and lattice oxygen atoms. The results reported herein open new prospects for SBA-16 as potential adsorbents for hydrogen storage.

  12. Hydrogen-powered lawn mower

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, K.; Lorenzoni, J.-L. (Geneva Univ. (Switzerland). Lab. de Cristallographie)

    1993-04-01

    We present a hydrogen-powered lawn mower which was adapted from a commercial model running on gasoline. The necessary modifications include adjustments to the carburettor and the insulation of a hydrogen reservoir containing about 5 kg of a metal hydride powder. Hydrogen is obtained by desorption of that powder at ambient temperature and 2 - 20 bar pressure. The reservoir is rechargeable at a hydrogen pressure of about 25 bar within less than 1 h. One charge lasts about 40 min. corresponding to about 800 m[sup 2] of cut lawn. The engine shows a reduced noise level and no tendency to backfiring. The prototype has run successfully for more than 1 year. (Author)

  13. Comparative studies of H absorption/desorption kinetics and evaporation of liquid lithium in different porous systems and free surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Oyarzabal, E., E-mail: eider.oyarzabal@externos.ciemat.es [Ass. Euratom-Ciemat, Av. Complutense 22, 28040 Madrid (Spain); Calle de Guzmán el Bueno, 133, 28003 Madrid (Spain); Martín-Rojo, A.B. [Ass. Euratom-Ciemat, Av. Complutense 22, 28040 Madrid (Spain); Calle de Guzmán el Bueno, 133, 28003 Madrid (Spain); Tabarés, F.L. [Ass. Euratom-Ciemat, Av. Complutense 22, 28040 Madrid (Spain)

    2017-04-15

    In the present work, a study of the two most relevant properties of liquid lithium with respect to its suitability as a Plasma Facing Component (PFC) element in a Reactor, namely, its evaporation rate and the uptake/release of hydrogen, eventually leading to the formation of a stable hydride was carried out for Li in different porous systems and Li as a free surface. These properties were characterized in a temperature range of 200–500 °C. The H{sub 2} absorption kinetics at low pressure (<1torr) were measured for the different studied porous systems and then outgassed. Particle balance and chemical analysis were used to assess the retention properties of lithium for each case. Thermal Desorption Spectroscopy (TDS) analysis was used for the assessment of possible hydride formation. Evaporation rates were determined by using a Quartz Microbalance (QMB). A significant reduction of the evaporation rate was observed when Li was trapped in a microstructure of sintered stainless steel with a characteristic porous size of 5–10 μm. On the other hand, a negligible rate of H{sub 2} uptake was found at temperatures above 500 °C in all cases.

  14. Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide

    Science.gov (United States)

    Deng, Meng; Wen, Hai-Lin; Dong, Xiao-Li; Li, Feng; Xu, Xin; Li, Hong; Li, Ji-Yao; Zhou, Xue-Dong

    2013-01-01

    Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents. PMID:23743618

  15. Electrochemical hydrogen storage properties of Mg100−xNix produced by hydriding combustion synthesis and mechanical milling

    Directory of Open Access Journals (Sweden)

    Delong Zhu

    2017-02-01

    Full Text Available In this work, Mg-based hydrogen storage composites with an initial 100-x: x (x=25, 32.3, 50, 66.7 of Mg:Ni molar ratio were prepared by HCS+MM and their phase compositions and electrochemical performances were investigated in detail. The results show that the composites with desirable constituents can be achieved by adjusting the molar ratio of the starting materials in the HCS process. Particularly, the HCS product of Mg67.7Ni32.3 consists of the principal phase Mg2NiH4 and minor phase Mg2NiH0.3. The dominate phase varies from Mg2NiH0.3 and MgH2 for the Mg enriched sample (x32.3. The MM modification not only brings about grain refinement of the alloys, but also leads to phase transformation of part Mg2NiH4 to Mg2NiH0.3 in the Mg67.7Ni32.3 sample. Electrochemical tests indicate that each sample can reach its maximum discharge capacity at the first cycle. Mg67.7Ni32.3 displays the highest discharge capacity as well as a superior electrochemical kinetics owing to its excellent H atom diffusion ability and lower charge-transfer resistance. The Mg67.7Ni32.3 provides the most optimized Mg/Ni atomic ratio considering the comprehensive electrochemical properties of all samples.

  16. Heat-integrated liquid-desorption exchanger (HILDE) for CO2 desorption

    NARCIS (Netherlands)

    Ham, L.V. van der; Khakharia, P.M.; Goetheer, E.L.V.

    2016-01-01

    A novel type of separating heat exchanger, called a heat-integrated liquid-desorption exchanger (HILDE), applied to a typical CO2 desorption process, has been investigated both numerically and experimentally. Process simulations, hydrodynamic and mass transfer experiments, and a preliminary cost

  17. Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 1. Structural, Hydrogen Storage, and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-11-01

    Full Text Available The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA were studied. Addition of Fe increases the lattice constants and abundance of the main Ce2Ni7 phase, decreases the NdNi3 phase abundance, and increases the CaCu5 phase when the Fe content is above 2.3 at%. For the gaseous phase hydrogen storage (H-storage, Fe incorporation does not change the storage capacity or equilibrium pressure, but it does decrease the change in both entropy and enthalpy. With regard to electrochemistry, >2.3 at% Fe decreases both the full and high-rate discharge capacities due to the deterioration in both bulk transport (caused by decreased secondary phase abundance and consequent lower synergetic effect and surface electrochemical reaction (caused by the lower volume of the surface metallic Ni inclusions. In a low-temperature environment (−40 °C, although Fe increases the reactive surface area, it also severely hinders the ability of the surface catalytic, leading to a net increase in surface charge-transfer resistance. Even though Fe increases the abundance of the beneficial Ce2Ni7 phase with a trade-off for the relatively unfavorable NdNi3 phase, it also deteriorates the electrochemical performance due to a less active surface. Therefore, further surface treatment methods that are able to increase the surface catalytic ability in Fe-containing superlattice alloys and potentially reveal the positive contributions that Fe provides structurally are worth investigating in the future.

  18. Effects of reaction conditions on hydrogen production and carbon nanofiber properties generated by methane decomposition in a fixed bed reactor using a NiCuAl catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suelves, I.; Pinilla, J.L.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma Castan, 4, 50015 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Marie Curie 2, 28049 Madrid (Spain)

    2009-07-01

    In this paper, the results obtained in the catalytic decomposition of methane in a fixed bed reactor using a NiCuAl catalyst prepared by the fusion method are presented. The influences of reaction temperature and space velocity on hydrogen concentration in the outlet gases, as well as on the properties of the carbon produced, have been investigated. Reaction temperature and the space velocity both increase the reaction rate of methane decomposition, but also cause an increase in the rate of catalyst deactivation. Under the operating conditions used, the carbon product is mainly deposited as nanofibers with textural properties highly correlated with the degree of crystallinity. (author)

  19. Investigations on ion-beam induced desorption from cryogenic surfaces; Untersuchungen zu ionenstrahlinduzierter Desorption von kryogenen Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Christoph

    2017-07-03

    pumps can be taken into account. This method can be extended to any desorption experiment employing the single shot method for measurement. Of special interest for the operation of the SIS100 at high intensities is the minimization of desorption from cryogenic surfaces. A previous examination of this topic found a breakdown of the familiar scaling of the desorption yield with the beam's energy loss for cryogenic targets. Further examination of this effect with the techniques described above is another goal of this thesis. Simultaneously, desorption measurements at room temperature for several other targets have been conducted. An unexpected result of these experiments is the influence of target surface properties, which was found to be very weak in comparison to previous results. The methods developed during this thesis, along with the results gained by their application, represent another step towards the comprehension of (heavy) ion beam induced desorption.

  20. Reversible hydrogen storage in Mg(BH4)2/carbon nanocomposites

    NARCIS (Netherlands)

    Yan, Y.; Au, Y.S.|info:eu-repo/dai/nl/328200360; Rentsch, D.; Remhof, A.; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; Züttel, A.

    2013-01-01

    Mg(BH4)2 exhibits a high hydrogen content of 14.9 wt% and thermodynamic stability in the overall decomposition reaction that corresponds to hydrogen desorption at around room temperature. However, the potential applications in hydrogen storage are restricted by high kinetic barriers. In this study,

  1. Interface effects in NaAlH4-carbon nanocomposites for hydrogen storage

    NARCIS (Netherlands)

    Gao, Jinbao|info:eu-repo/dai/nl/315029633; Ngene, Peter|info:eu-repo/dai/nl/314121684; Herrich, Monika; Xia, Wei; Gutfleisch, Oliver; Muhler, Martin; De Jong, Krijn P.|info:eu-repo/dai/nl/06885580X; De Jongh, Petra E.|info:eu-repo/dai/nl/186125372

    2014-01-01

    For practical solid-state hydrogen storage, reversibility under mild conditions is crucial. Complex metal hydrides such as NaAlH4 and LiBH4 have attractive hydrogen contents. However, hydrogen release and especially uptake after desorption are sluggish and require high temperatures and pressures.

  2. Thermodynamic and dynamic dielectric properties of one-dimensional hydrogen bonded ferroelectric of PbHPO4-type

    National Research Council Canada - National Science Library

    I.R. Zachek; R.R. Levitskii; Ya. Shchur; O.B. Bilenka

    2014-01-01

    Within the modified model of proton ordering of one-dimensional ferroelectric having hydrogen bonds of PbHPO4-type, their thermodynamic and dynamic characteristics are studied and calculated taking...

  3. Catalyzed Nano-Framework Stablized High Density Reversible Hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xia [value too long for type character varying(50); Opalka, Susanne M.; Mosher, Daniel A; Laube, Bruce L; Brown, Ronald J; Vanderspurt, Thomas H; Arsenault, Sarah; Wu, Robert; Strickler, Jamie; Ronnebro, Ewa; Boyle, Tim; Cordaro, Joseph

    2010-06-30

    A wide range of high capacity on-board rechargeable material candidates have exhibited non-ideal behavior related to irreversible hydrogen discharge / recharge behavior, and kinetic instability or retardation. This project addresses these issues by incorporating solvated and other forms of complex metal hydrides, with an emphasis on borohydrides, into nano-scale frameworks of low density, high surface area skeleton materials to stabilize, catalyze, and control desorption product formation associated with such complex metal hydrides. A variety of framework chemistries and hydride / framework combinations were investigated to make a relatively broad assessment of the method's potential. In this project, the hydride / framework interactions were tuned to decrease desorption temperatures for highly stable compounds or increase desorption temperatures for unstable high capacity compounds, and to influence desorption product formation for improved reversibility. First principle modeling was used to explore heterogeneous catalysis of hydride reversibility by modeling H2 dissociation, hydrogen migration, and rehydrogenation. Atomic modeling also demonstrated enhanced NaTi(BH4)4 stabilization at nano-framework surfaces modified with multi-functional agents. Amine multi-functional agents were found to have more balanced interactions with nano-framework and hydride clusters than other functional groups investigated. Experimentation demonstrated that incorporation of Ca(BH4)2 and Mg(BH4)2 in aerogels enhanced hydride desorption kinetics. Carbon aerogels were identified as the most suitable nano-frameworks for hydride kinetic enhancement and high hydride loading. High loading of NaTi(BH4)4 ligand complex in SiO2 aerogel was achieved and hydride stability was improved with the aerogel. Although improvements of desorption kinetics was observed, the incorporation of

  4. Hydrogen bonding and transportation properties of water confined in the single-walled carbon nanotube in the pulse-field

    Science.gov (United States)

    Zhou, Min; Hu, Ying; Liu, Jian-chuan; Cheng, Ke; Jia, Guo-zhu

    2017-10-01

    In this paper, molecular dynamics simulations were performed to investigate the transportation and hydrogen bonding dynamics of water confined in (6, 6) single-walled carbon nanotube (SWCNT) in the absence and presence of time-dependent pulse-field. The effects of pulse-field range from microwave to ultraviolet frequency on the diffusivity and hydrogen bonding of confined water were analyzed. The significant confinement effect due to the narrow space inside SWCNT was observed.

  5. Development of Innovating Materials for Distributing Mixtures of Hydrogen and Natural Gas. Study of the Barrier Properties and Durability of Polymer Pipes

    Directory of Open Access Journals (Sweden)

    Klopffer Marie-Hélène

    2015-02-01

    Full Text Available With the growing place taken by hydrogen, a question still remains about its delivery and transport from the production site to the end user by employing the existing extensive natural gas pipelines. Indeed, the key challenge is the significant H2 permeation through polymer infrastructures (PolyEthylene (PE pipes, components such as connecting parts. This high flow rate of H2 through PE has to be taken into account for safety and economic requirements. A 3-year project was launched, the aim of which was to develop and assess material solutions to cope with present problems for hydrogen gas distribution and to sustain higher pressure compared to classical high density polyethylene pipe. This project investigated pure hydrogen gas and mixtures with natural gas (20% of CH4 and 80% of H2 in pipelines with the aim to select engineering polymers which are more innovative than polyethylene and show outstanding properties, in terms of permeation, basic mechanical tests but also more specific characterizations such as long term ageing and behaviour. The adequate benches, equipments and scientific approach for materials testing had been developed and validated. In this context, the paper will focus on the evaluation of the barrier properties of 3 polymers (PE, PA11 and PAHM. Experiments were performed for pure H2 and CH4 and also in the presence of mixtures of hydrogen and natural gas in order to study the possible mixing effects of gases. It will report some round-robin tests that have been carried out. Secondly, by comparing data obtained on film, polymer membrane and on pipe section, the influence of the polymer processing will be studied. Innovative multilayers systems will be proposed and compared on the basis of the results obtained on monolayer systems. Finally, the evolution of the transport properties of the studied polymers with an ageing under representative service conditions will be discussed.

  6. Gigacycle Fatigue Properties of Hydrogen-Charged JIS-SCM440 Low-Alloy Steel Under Ultrasonic Fatigue Testing

    Science.gov (United States)

    Furuya, Yoshiyuki; Hirukawa, Hisashi; Hayakawa, Masao

    2010-09-01

    Gigacycle fatigue tests were conducted on hydrogen-charged low-alloy steel. In this study, high- and low-strength specimens were prepared to investigate the effects of hydrogen on internal and surface fractures, respectively. The fatigue tests were conducted mainly by ultrasonic fatigue testing at 20 kHz and additionally by conventional servohydraulic fatigue testing at 50 Hz. All high-strength specimens revealed internal fractures. The fatigue strength of the hydrogen-charged specimens was much lower than that of the uncharged specimens. In the low-strength specimens, the uncharged specimens revealed surface fractures in the short-life regions in addition to internal fractures in the long-life regions. However, the hydrogen-charged specimens revealed internal fractures only that were combined with a much lower fatigue strength. The difference in fracture surfaces was small between the hydrogen-charged and the uncharged specimens, whereas the optically dark areas of the hydrogen-charged specimens seemed smaller than those of the uncharged specimens.

  7. Hydrogenated TiO{sub 2} film for enhancing photovoltaic properties of solar cells and self-sensitized effect

    Energy Technology Data Exchange (ETDEWEB)

    He, Hongcai; Yang, Kui; Wang, Ning, E-mail: ning-wang@uestc.edu.cn; Luo, Feifei; Chen, Haijun [State Key Laboratory of Electronic Thin Films and Integrated Devices and School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2013-12-07

    Hydrogenated TiO{sub 2} film was obtained by annealing TiO{sub 2} film at 350 °C for 2 h with hydrogen, and TiO{sub 2} films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO{sub 2} film and pristine TiO{sub 2} film. Through optical and electrochemical characterization, the hydrogenated TiO{sub 2} film showed enhanced absorption and narrowed band gap, as well as reduced TiO{sub 2} surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO{sub 2} as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO{sub 2} film, which excited electrons injecting internal conduction band of TiO{sub 2} to generate more photocurrent.

  8. Material synthesis and hydrogen storage of palladium-rhodium alloy.

    Energy Technology Data Exchange (ETDEWEB)

    Lavernia, Enrique J. (University of California, Davis); Yang, Nancy Y. C.; Ong, Markus D. (Whithworth University, Spokane, WA)

    2011-08-01

    Pd and Pd alloys are candidate material systems for Tr or H storage. We have actively engaged in material synthesis and studied the material science of hydrogen storage for Pd-Rh alloys. In collaboration with UC Davis, we successfully developed/optimized a supersonic gas atomization system, including its processing parameters, for Pd-Rh-based alloy powders. This optimized system and processing enable us to produce {le} 50-{mu}m powders with suitable metallurgical properties for H-storage R&D. In addition, we studied hydrogen absorption-desorption pressure-composition-temperature (PCT) behavior using these gas-atomized Pd-Rh alloy powders. The study shows that the pressure-composition-temperature (PCT) behavior of Pd-Rh alloys is strongly influenced by its metallurgy. The plateau pressure, slope, and H/metal capacity are highly dependent on alloy composition and its chemical distribution. For the gas-atomized Pd-10 wt% Rh, the absorption plateau pressure is relatively high and consistent. However, the absorption-desorption PCT exhibits a significant hysteresis loop that is not seen from the 30-nm nanopowders produced by chemical precipitation. In addition, we observed that the presence of hydrogen introduces strong lattice strain, plastic deformation, and dislocation networking that lead to material hardening, lattice distortions, and volume expansion. The above observations suggest that the H-induced dislocation networking is responsible for the hysteresis loop seen in the current atomized Pd-10 wt% Rh powders. This conclusion is consistent with the hypothesis suggested by Flanagan and others (Ref 1) that plastic deformation or dislocations control the hysteresis loop.

  9. Analysis of electro-permeation of hydrogen in metallic alloys.

    Science.gov (United States)

    Raina, A; Deshpande, V S; Fleck, N A

    2017-07-28

    A reaction-diffusion type modelling framework is presented to analyse both electro-permeation (EP) and thermal desorption spectrometry (TDS) measurements of hydrogen in metallic alloys. It is assumed that the kinetics of hydrogen motion is governed by diffusion through the lattice, along with trapping/detrapping at specific sites such as dislocations, grain boundaries, etc. It is shown that the trapping and detrapping rates are typically much faster than the diffusion rate, and consequently a simplification of the governing equations suffices such that local equilibrium exists between lattice and trapped hydrogen. Using this local equilibrium assumption, we then present an asymptotic analysis of the governing kinetic equation for the EP test. This asymptotic analysis reveals that four regimes of behaviour exist, ranging from negligible trapping to the complete filling of deep traps. The analysis suggests that EP tests should be so-arranged that three regimes of behaviour are spanned, in order to extract the relevant material properties associated with hydrogen transport. The numerical solutions presented in this study support the asymptotic analysis. The hydrogen kinetics framework is also deployed to analyse both EP and TDS tests on the same martensitic steel. The EP measurements all lie in regime I and are thus insufficient to uniquely determine both the trap density and binding energy. Reasonable agreement is obtained between measurements and numerical predictions of TDS tests using parameters estimated from the EP tests. Further improvements in measurements are required to confirm the fidelity of this modelling approach.This article is part of the themed issue 'The challenges of hydrogen and metals'. © 2017 The Author(s).

  10. DIRAC: A new version of computer algebra tools for studying the properties and behavior of hydrogen-like ions

    Science.gov (United States)

    McConnell, Sean; Fritzsche, Stephan; Surzhykov, Andrey

    2010-03-01

    During recent years, the DIRAC package has proved to be an efficient tool for studying the structural properties and dynamic behavior of hydrogen-like ions. Originally designed as a set of MAPLE procedures, this package provides interactive access to the wave and Green's functions in the non-relativistic and relativistic frameworks and supports analytical evaluation of a large number of radial integrals that are required for the construction of transition amplitudes and interaction cross sections. We provide here a new version of the DIRAC program which is developed within the framework of MATHEMATICA (version 6.0). This new version aims to cater to a wider community of researchers that use the MATHEMATICA platform and to take advantage of the generally faster processing times therein. Moreover, the addition of new procedures, a more convenient and detailed help system, as well as source code revisions to overcome identified shortcomings should ensure expanded use of the new DIRAC program over its predecessor. New version program summaryProgram title: DIRAC Catalogue identifier: ADUQ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUQ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 45 073 No. of bytes in distributed program, including test data, etc.: 285 828 Distribution format: tar.gz Programming language: Mathematica 6.0 or higher Computer: All computers with a license for the computer algebra package Mathematica (version 6.0 or higher) Operating system: Mathematica is O/S independent Classification: 2.1 Catalogue identifier of previous version: ADUQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 165 (2005) 139 Does the new version supersede the previous version?: Yes Nature of problem: Since the early days of quantum mechanics, the

  11. 2014 Accomplishments-Tritium aging studies on stainless steel: Fracture toughness properties of forged stainless steels-Effect of hydrogen, forging strain rate, and forging temperature

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-02-01

    Forged stainless steels are used as the materials of construction for tritium reservoirs. During service, tritium diffuses into the reservoir walls and radioactively decays to helium-3. Tritium and decay helium cause a higher propensity for cracking which could lead to a tritium leak or delayed failure of a tritium reservoir. The factors that affect the tendency for crack formation and propagation include: Environment; steel type and microstructure; and, vessel configuration (geometry, pressure, residual stress). Fracture toughness properties are needed for evaluating the long-term effects of tritium on their structural properties. Until now, these effects have been characterized by measuring the effects of tritium on the tensile and fracture toughness properties of specimens fabricated from experimental forgings in the form of forward-extruded cylinders. A key result of those studies is that the long-term cracking resistance of stainless steels in tritium service depends greatly on the interaction between decay helium and the steels’ forged microstructure. New experimental research programs are underway and are designed to measure tritium and decay helium effects on the cracking properties of stainless steels using actual tritium reservoir forgings instead of the experimental forgings of past programs. The properties measured should be more representative of actual reservoir properties because the microstructure of the specimens tested will be more like that of the tritium reservoirs. The programs are designed to measure the effects of key forging variables on tritium compatibility and include three stainless steels, multiple yield strengths, and four different forging processes. The effects on fracture toughness of hydrogen and crack orientation were measured for type 316L forgings. In addition, hydrogen effects on toughness were measured for Type 304L block forgings having two different yield strengths. Finally, fracture toughness properties of type 304L

  12. Desorption of 137Cs+ from mosses

    Directory of Open Access Journals (Sweden)

    OLGICA NEDIC

    2002-09-01

    Full Text Available Mosses are biomonitors that accumulate large amounts of various pollutants, including radionuclides. In this work we investigated the possibility of 137Cs extraction from mosses, as well as the significance of species specificity on the efficiency of 137Cs desorption. Salt and acid solutions were used as extraction media. It was shown that a 5 % solution of both ammonium oxalate and phosphoric acid was able to desorb 81.8 % of 137Cs+ from Homalothecium sericeum, which was 39.9 % more than desorption from water. At the same time, most of the desorbed 137Cs+ was incorporated in crystals that precipitated from the solution. An interspecies difference in respect to 137Cs+ desorption was noticed.

  13. Ionic Adsorption and Desorption of CNT Nanoropes

    Directory of Open Access Journals (Sweden)

    Jun-Jun Shang

    2016-09-01

    Full Text Available A nanorope is comprised of several carbon nanotubes (CNTs with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment.

  14. Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

    CERN Document Server

    Seenithurai, Sonai

    2016-01-01

    Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3 - 8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions.

  15. Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study

    Science.gov (United States)

    Seenithurai, Sonai; Chai, Jeng-Da

    2016-01-01

    Due to the presence of strong static correlation effects and noncovalent interactions, accurate prediction of the electronic and hydrogen storage properties of Li-adsorbed acenes with n linearly fused benzene rings (n = 3–8) has been very challenging for conventional electronic structure methods. To meet the challenge, we study these properties using our recently developed thermally-assisted-occupation density functional theory (TAO-DFT) with dispersion corrections. In contrast to pure acenes, the binding energies of H2 molecules on Li-adsorbed acenes are in the ideal binding energy range (about 20 to 40 kJ/mol per H2). Besides, the H2 gravimetric storage capacities of Li-adsorbed acenes are in the range of 9.9 to 10.7 wt%, satisfying the United States Department of Energy (USDOE) ultimate target of 7.5 wt%. On the basis of our results, Li-adsorbed acenes can be high-capacity hydrogen storage materials for reversible hydrogen uptake and release at ambient conditions. PMID:27609626

  16. Long-Term Cycling of the Magnesium Hydrogen System

    DEFF Research Database (Denmark)

    Pedersen, Allan Schrøder; Kjøller, John; Larsen, Bent

    1984-01-01

    Magnesium powder with a grain size of approximately 50γm was hydrogenated for 30 min and dehydrogenated the same time at 390°C, 515 times. A moderate loss in hydrogen storage capacity was observed and was ascribed to a measured decrease in reaction kinetics as the cycle number increased. The time...... for maximum hydrogen absorption was found to depend significantly on cycle number while the time for maximum desorption was found to be virtually independent of cycle number....

  17. Uranium for hydrogen storage applications : a materials science perspective.

    Energy Technology Data Exchange (ETDEWEB)

    Shugard, Andrew D.; Tewell, Craig R.; Cowgill, Donald F.; Kolasinski, Robert D.

    2010-08-01

    Under appropriate conditions, uranium will form a hydride phase when exposed to molecular hydrogen. This makes it quite valuable for a variety of applications within the nuclear industry, particularly as a storage medium for tritium. However, some aspects of the U+H system have been characterized much less extensively than other common metal hydrides (particularly Pd+H), likely due to radiological concerns associated with handling. To assess the present understanding, we review the existing literature database for the uranium hydride system in this report and identify gaps in the existing knowledge. Four major areas are emphasized: {sup 3}He release from uranium tritides, the effects of surface contamination on H uptake, the kinetics of the hydride phase formation, and the thermal desorption properties. Our review of these areas is then used to outline potential avenues of future research.

  18. Ionization properties of mixed lipid membranes: a Gouy-Chapman model of the electrostatic-hydrogen bond switch.

    Science.gov (United States)

    Mengistu, Demmelash H; Kooijman, Edgar E; May, Sylvio

    2011-08-01

    The dissociation state of phosphatidic acid (PA) in a lipid bilayer is governed by the competition of proton binding and formation of a hydrogen bond through a mechanism termed the electrostatic-hydrogen bond switch. This mechanism has been suggested to provide the basis for the specific recognition of PA by proteins. Even in bare lipid bilayers the electrostatic-hydrogen bond switch is present if the membrane contains lipids like phosphatidylethanolamine that act as hydrogen bond donors. In this case, the dissociation state (pK(a)) of PA depends strongly on membrane composition. In the present work we incorporate the electrostatic-hydrogen bond switch mechanism into the Gouy-Chapman model for a membrane that is composed of PA and a hydrogen bond-donating zwitterionic lipid. To this end, our model integrates into the Gouy-Chapman approach a recently suggested electrostatic model for zwitterionic lipids. Hydrogen bond formation is incorporated phenomenologically as an additional non-electrostatic interaction between the phosphomonoester headgroup of PA and the zwitterionic lipid headgroup. We express the energetics of the composite membrane in terms of a free energy functional whose minimization leads to a modified non-linear Poisson-Boltzmann equation that we have solved numerically. Our calculations focus on the influence of the membrane environment on the dissociation state of PA. This influence can be expressed as a shift of the second pK(a) of PA, which we calculate as function of membrane composition, following experimental observation. The shift is large and negative if PA is the minor component in the membrane, and it changes over four pH units as function of the mole fraction of PA in the membrane. In contrast, the shift of the second pK(a) of PA remains small and is always positive if the zwitterionic lipid is unable to act as hydrogen bond donor. Hence, we find that the electrostatic-hydrogen bond switch mechanism regulates the dissociation state of PA

  19. Influence of intramolecular hydrogen bonding interaction on the molecular properties of N-p-tolyl-5-oxo pyrrolidine-3-carboxylic acid: A theoretical and experimental study

    Science.gov (United States)

    Muthuraja, P.; Shanmugavadivu, T.; Joselin Beaula, T.; Bena Jothy, V.; Dhandapani, M.

    2018-01-01

    N-p-tolyl-5-oxo pyrrolidine-3-carboxylic acid (TOPCA) was synthesized by Michael addition-cyclo condensation. The molecular structure of TOPCA was optimized by B3LYP method with 6-311G(d,p) and aug-cc-pVDZ (Dunning) basis sets as well as CAM-B3LYP method with 6-311G(d,p) basis set. In addition, MEP, CHELPG and NBO analyses were carried out to understand the influence of hydrogen bonding interactions. The molecular structure of TOPCA is governed by intramolecular hydrogen bonding interactions (Csbnd H…O) which influence charge transfer in TOPCA. The Csbnd H…O interactions stimulate the emission property of TOPCA excited at 380 nm. Intramolecular H- bonding and charge transfer induce the second hyperpolarizability in TOPCA.

  20. Physical, chemical and microbiological properties of mixed hydrogenated palm kernel oil and cold-pressed rice bran oil as ingredients in non-dairy creamer

    Directory of Open Access Journals (Sweden)

    Kunakorn Katsri

    2014-02-01

    Full Text Available The physical, chemical and microbiological properties of hydrogenated palm kernel oil (PKO and cold-pressed rice bran oil (RBOas ingredients in the production of liquid and powdered non-dairy creamer (coffee whitener were studied. The mixing ratios between hydrogenated PKO and cold-pressed RBO were statistically designed as of 100:0, 90:10,80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90 and 0:100.The color, absorbanceand viscosity of the mixtures were investigated. As the ratio of cold-pressed RBO increased, the color became darker (L*of 93.06 to 86.25 and the absorbance significantly increased, while the viscosity of the mixtures of 20:80, 10:90 and 0:100 (54 cp. were the highest amongst the ratios tested.The hydrogenated PKO and cold-pressed RBO mixtures were further chemically tested for fatty acids, -oryzanol, -tocopherol, trans-fat contents andantioxidant activity. There were 10 fatty acids present in hydrogenated PKO with saturated fatty acid being the most predominant. Comparatively, there were only 5 fatty acids found in cold-pressed RBO with monounsaturated fatty acid being the major fatty acid. -Oryzanol and -tocopherol contents were higher with increasingcold-pressed RBO from 0-100% (0 to 1,155.00 mg/100g oil and 0.09 to 30.82 mg/100g oil, respectively. Antioxidant activity was increased with increasing cold-pressed RBO from 0-100% (9.26 to 94.24%.The pure hydrogenated PKO contained higher trans-fat content than that of the 90:10 and 80:20 mixtures (2.73, 1.93 and 1.85mg/100g oil,respectively while other samples had no trans-fat. No microorganisms were present in any of the samples.Therefore, substitution of hydrogenated PKO by cold-pressed RBO from 30-100% would offer more nutritional values and better chemical and physical properties of non-dairy creamer.

  1. Hydrogen sensing properties of nanocomposite graphene oxide/Co-based metal organic frameworks (Co-MOFs@GO)

    Science.gov (United States)

    Fardindoost, Somayeh; Hatamie, Shadie; Iraji Zad, Azam; Razi Astaraei, Fatemeh

    2018-01-01

    This paper reports on hydrogen sensing based graphene oxide hybrid with Co-based metal organic frameworks (Co-MOFs@GO) prepared by the hydrothermal process. The texture and morphology of the hybrid were characterized by powder x-ray diffraction, scanning electron microscopy and Brunauer–Emmett–Teller analysis. Porous flower like structures assembled from Co-MOFs and GO flakes with sufficient specific surface area are obtained, which are ideal for gas molecules diffusion and interactions. Sensing performance of Co-MOFs@GO were tested and also improved by sputtering platinum (Pt) as a catalyst. The Pt-sputtered Co-MOFs@GO show outstanding hydrogen resistive-sensing with response and recovery times below 12 s at 15 °C. Also, they show stable, repeatable and selective responses to the target gas which make it suitable for the development of a high performance hydrogen sensor.

  2. Hydrogen Fuelling Stations

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard

    This thesis concerns hydrogen fuelling stations from an overall system perspective. The study investigates thermodynamics and energy consumption of hydrogen fuelling stations for fuelling vehicles for personal transportation. For the study a library concerning the components in a hydrogen fuelling...... station has been developed in Dymola. The models include the fuelling protocol (J2601) for hydrogen vehicles made by Society of Automotive Engineers (SAE) and the thermodynamic property library CoolProp is used for retrieving state point. The components in the hydrogen fuelling library are building up....... A system consisting of one high pressure storage tank is used to investigate the thermodynamics of fuelling a hydrogen vehicle. The results show that the decisive parameter for how the fuelling proceeds is the pressure loss in the vehicle. The single tank fuelling system is compared to a cascade fuelling...

  3. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  4. Prospects for hydrogen storage in graphene.

    Science.gov (United States)

    Tozzini, Valentina; Pellegrini, Vittorio

    2013-01-07

    Hydrogen-based fuel cells are promising solutions for the efficient and clean delivery of electricity. Since hydrogen is an energy carrier, a key step for the development of a reliable hydrogen-based technology requires solving the issue of storage and transport of hydrogen. Several proposals based on the design of advanced materials such as metal hydrides and carbon structures have been made to overcome the limitations of the conventional solution of compressing or liquefying hydrogen in tanks. Nevertheless none of these systems are currently offering the required performances in terms of hydrogen storage capacity and control of adsorption/desorption processes. Therefore the problem of hydrogen storage remains so far unsolved and it continues to represent a significant bottleneck to the advancement and proliferation of fuel cell and hydrogen technologies. Recently, however, several studies on graphene, the one-atom-thick membrane of carbon atoms packed in a honeycomb lattice, have highlighted the potentialities of this material for hydrogen storage and raise new hopes for the development of an efficient solid-state hydrogen storage device. Here we review on-going efforts and studies on functionalized and nanostructured graphene for hydrogen storage and suggest possible developments for efficient storage/release of hydrogen under ambient conditions.

  5. Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide

    Science.gov (United States)

    Sofyan, Nofrijon Bin Imam

    The effect of hydrogen peroxide used as a decontaminant agent on selected aircraft metallic materials has been investigated. The work is divided into three sections; bacterial attachment behavior onto an austenitic stainless steel 304 surface; effect of decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials of two aluminum alloys, i.e. 2024-T3 and 7075-T6, and an austenitic stainless steel 304 as used in galley and lavatory surfaces; and copper dissolution rate into hydrogen peroxide. With respect to bacterial attachment, the results show that surface roughness plays a role in the attachment of bacteria onto metallic surfaces at certain extent. However, when the contact angle of the liquid on a surface increased to a certain degree, detachment of bacteria on that surface became more difficult. In its relation to the decontamination process, the results show that a corrosion site, especially on the austenitic stainless steel 304 weld and its surrounding HAZ area, needs more attention because it could become a source or a harborage of bio-contaminant agent after either incidental or intentional bio-contaminant delivery. On the effect of the decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials, the results show that microstructural effects are both relatively small in magnitude and confined to a region immediately adjacent to the exposed surface. No systematic effect is found on the tensile properties of the three alloys under the conditions examined. The results of this investigation are promising with respect to the application of vapor phase hydrogen peroxide as a decontaminant agent to civilian aircraft, in that even under the most severe circumstances that could occur; only very limited damage was observed. The results from the dissolution of copper by concentrated liquid hydrogen peroxide showed that the rate of copper dissolution increased for

  6. Product desorption limitations in selective photocatalytic oxidation

    NARCIS (Netherlands)

    Renckens, T.J.A.; Almeida, A.R.; Almeida, A.R.; Damen, M.R.; Kreutzer, M.T.; Mul, Guido

    2010-01-01

    The rate of photocatalytic processes can be significantly improved if strongly bound products rapidly desorb to free up active sites. This paper deals with the rate of desorption of cyclohexanone, the product of the liquid-phase photo-oxidation of cyclohexane. Dynamic step-response and

  7. Quantum theory of laser-stimulated desorption

    Science.gov (United States)

    Slutsky, M. S.; George, T. F.

    1978-01-01

    A quantum theory of laser-stimulated desorption (LSDE) is presented and critically analyzed. It is shown how LSDE depends on laser-pulse characteristics and surface-lattice dynamics. Predictions of the theory for a Debye model of the lattice dynamics are compared to recent experimental results.

  8. Recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Wang, Jing; Liu, Qian; Liang, Yong; Jiang, Guibin

    2016-04-01

    Carbon nanomaterials have attracted great interest over past decades owing to their unique physical properties, versatile functionalization chemistry, and biological compatibility. In this article, we review recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry (LDI MS). Various types of carbon nanomaterials, including fullerenes, carbon nanotubes, graphene, carbon nanodots, nanodiamond, nanofibers, nanohorns, and their derivative forms, are involved. The applications of these materials as new matrices or probes in matrix-assisted or surface-enhanced laser desorption/ionization mass spectrometry (MALDI or SELDI MS) are discussed. Finally, we summarize current challenges and give our perspectives on the future of applications of carbon nanomaterials in LDI MS.

  9. Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

    OpenAIRE

    Laptev, Roman S.; Viktor N. Kudiiarov; Bordulev, Yuri S.; Mikhaylov, Andrey A.; Andrey M. Lider

    2017-01-01

    Titanium and its alloys are promising materials for hydrogen storage. However, hydrogen penetration accompanies the exploitation of hydrogen storage alloys. In particular, hydrogen penetration and accumulation in titanium alloys changes their mechanical properties. Therefore, the research works of such materials are mainly focused on improving the reversibility of hydrogen absorption-liberation processes, increasing the thermodynamic characteristics of the alloys, and augmenting their hydroge...

  10. Improved adhesion and tribological properties of fast-deposited hard graphite-like hydrogenated amorphous carbon films

    NARCIS (Netherlands)

    Zaharia, T.; Kudlacek, P.; Creatore, M.; Groenen, R.; Persoone, P.; M. C. M. van de Sanden,

    2011-01-01

    Graphite-like hard hydrogenated amorphous carbon (a-C:H) was deposited using an Ar-C(2)H(2) expanding thermal plasma chemical vapour deposition (ETP-CVD) process. The relatively high hardness of the fast deposited a-C:H material leads to high compressive stress resulting in poor adhesion between the

  11. Effects of absorbed hydrogen on the electronic properties of (Zr2Fe)(1-x)H(x) metallic glasses.

    Science.gov (United States)

    Novak, M; Kokanović, I

    2012-06-13

    The electrical conductivity (σ) of hydrogen doped (Zr(2)Fe)(1-x)H(x) metallic glasses has been measured in the temperature range from 290 down to 5 K. The decrease of the room temperature conductivity and the increase of its temperature coefficient are explained as consequences of increased disorder due to hydrogen doping. σ(T) for (Zr(2)Fe)(1-x)H(x) metallic glasses at low temperatures decreases with the increase of temperature, forming a minimum at T(min), before it starts a monotonic increase with increasing temperature. Both the functional forms and the magnitudes of the observed σ(T) are interpreted in terms of weak localization, electron-electron interaction and spin-fluctuation effects. Our results reveal that the electron-phonon scattering rate varies with the square of temperature from low temperatures up to 100 K and changes behaviour to a linear form at higher temperatures. At low temperatures, the minimum in σ(T) is shifted to higher temperatures, which is ascribed to the increase of the screening parameter of the Coulomb interaction F* associated with the enhancement of the spin fluctuations arising from the increase of the hydrogen doping. The spin-orbit scattering rate and the electron diffusion constant are reduced by hydrogen doping.

  12. [The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

    Science.gov (United States)

    Wang, Jue; Qiao, Guang-yan

    2013-04-01

    To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

  13. A synthesis method for cobalt doped carbon aerogels with high surface area and their hydrogen storage properties

    Energy Technology Data Exchange (ETDEWEB)

    Tian, H.Y.; Buckley, C.E. [Department of Imaging and Applied Physics, Curtin University of Technology, GPO Box U 1987, Perth 6845, WA (Australia); CSIRO National Hydrogen Materials Alliance, CSIRO Energy Centre, 10 Murray Dwyer Circuit, Steel River Estate, Mayfield West, NSW 2304 (Australia); Sheppard, D.A.; Paskevicius, M. [Department of Imaging and Applied Physics, Curtin University of Technology, GPO Box U 1987, Perth 6845, WA (Australia); Hanna, N. [CSIRO Process Science and Engineering, Waterford, WA (Australia)

    2010-12-15

    Carbon aerogels doped with nanoscaled Co particles were prepared by first coating activated carbon aerogels using a wet-thin layer coating process. The resulting metal-doped carbon aerogels had a higher surface area ({proportional_to}1667 m{sup 2} g{sup -1}) and larger micropore volume ({proportional_to}0.6 cm{sup 3} g{sup -1}) than metal-doped carbon aerogels synthesised using other methods suggesting their usefulness in catalytic applications. The hydrogen adsorption behaviour of cobalt doped carbon aerogel was evaluated, displaying a high {proportional_to}4.38 wt.% H{sub 2} uptake under 4.6 MPa at -196 C. The hydrogen uptake capacity with respect to unit surface area was greater than for pure carbon aerogel and resulted in {proportional_to}1.3 H{sub 2} (wt. %) per 500 m{sup 2} g{sup -1}. However, the total hydrogen uptake was slightly reduced as compared to pure carbon aerogel due to a small reduction in surface area associated with cobalt doping. The improved adsorption per unit surface area suggests that there is a stronger interaction between the hydrogen molecules and the cobalt doped carbon aerogel than for pure carbon aerogel. (author)

  14. Sputtered Pd as Hydrogen Storage for a Chip-Integrated Microenergy System

    Directory of Open Access Journals (Sweden)

    E. Slavcheva

    2014-01-01

    Full Text Available The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD, scanning electron microscopy (SEM, and atomic force microscopy (AMF. The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis and discharging (fuel cell operative mode at ambient conditions demonstrating a stable recycling performance.

  15. Curvature and ionization-induced reversible hydrogen storage in metalized hexagonal B36

    Science.gov (United States)

    Liu, Chun-Sheng; Wang, Xiangfu; Ye, Xiao-Juan; Yan, Xiaohong; Zeng, Zhi

    2014-11-01

    The synthesis of quasiplanar boron clusters (B36) with a central hexagonal hole provides the first experimental evidence that a single-atomic-layer borophene with hexagonal vacancies is potentially viable [Z. Piazza, H. Hu, W. Li, Y. Zhao, J. Li, and L. S. Wang, Nat. Commun. 5, 3113 (2014)]. However, owing to the hexagonal holes, tunning the electronic and physical properties of B36 through chemical modifications is not fully understood. Based on (van der Waals corrected-) density functional theory, we show that Li adsorbed on B36 and B^-_{36} clusters can serve as reversible hydrogen storage media. The present results indicate that the curvature and ionization of substrates can enhance the bond strength of Li due to the energetically favorable B 2p-Li 2p orbitals hybridization. Both the polarization mechanism and the orbital hybridization between H-s orbitals and Li-2s2p orbitals contribute to the adsorption of H2 molecules and the resulting adsorption energy lies between the physisorbed and chemisorbed states. Interestingly, the number of H2 in the hydrogen storage medium can be measured by the appearance of the negative differential resistance behavior at different bias voltage regions. Furthermore, the cluster-assembled hydrogen storage materials constructed by metalized B36 clusters do not cause a decrease in the number of adsorbed hydrogen molecules per Li. The system reported here is favorable for the reversible hydrogen adsorption/desorption at ambient conditions.

  16. Sputtered Pd as hydrogen storage for a chip-integrated microenergy system.

    Science.gov (United States)

    Slavcheva, E; Ganske, G; Schnakenberg, U

    2014-01-01

    The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AMF). The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis) and discharging (fuel cell) operative mode at ambient conditions demonstrating a stable recycling performance.

  17. Curvature and ionization-induced reversible hydrogen storage in metalized hexagonal B36.

    Science.gov (United States)

    Liu, Chun-Sheng; Wang, Xiangfu; Ye, Xiao-Juan; Yan, Xiaohong; Zeng, Zhi

    2014-11-21

    The synthesis of quasiplanar boron clusters (B36) with a central hexagonal hole provides the first experimental evidence that a single-atomic-layer borophene with hexagonal vacancies is potentially viable [Z. Piazza, H. Hu, W. Li, Y. Zhao, J. Li, and L. S. Wang, Nat. Commun. 5, 3113 (2014)]. However, owing to the hexagonal holes, tunning the electronic and physical properties of B36 through chemical modifications is not fully understood. Based on (van der Waals corrected-) density functional theory, we show that Li adsorbed on B36 and B36 (-) clusters can serve as reversible hydrogen storage media. The present results indicate that the curvature and ionization of substrates can enhance the bond strength of Li due to the energetically favorable B 2p-Li 2p orbitals hybridization. Both the polarization mechanism and the orbital hybridization between H-s orbitals and Li-2s2p orbitals contribute to the adsorption of H2 molecules and the resulting adsorption energy lies between the physisorbed and chemisorbed states. Interestingly, the number of H2 in the hydrogen storage medium can be measured by the appearance of the negative differential resistance behavior at different bias voltage regions. Furthermore, the cluster-assembled hydrogen storage materials constructed by metalized B36 clusters do not cause a decrease in the number of adsorbed hydrogen molecules per Li. The system reported here is favorable for the reversible hydrogen adsorption/desorption at ambient conditions.

  18. Correlations for determining thermodynamic properties of hydrogen-helium gas mixtures at temperatures from 7,000 to 35,000 K

    Science.gov (United States)

    Zoby, E. V.; Gnoffo, P. A.; Graves, R. A., Jr.

    1976-01-01

    Simple relations for determining the enthalpy and temperature of hydrogen-helium gas mixtures were developed for hydrogen volumetric compositions from 1.0 to 0.7. These relations are expressed as a function of pressure and density and are valid for a range of temperatures from 7,000 to 35,000 K and pressures from 0.10 to 3.14 MPa. The proportionality constant and exponents in the correlation equations were determined for each gas composition by applying a linear least squares curve fit to a large number of thermodynamic calculations obtained from a detailed computer code. Although these simple relations yielded thermodynamic properties suitable for many engineering applications, their accuracy was improved significantly by evaluating the proportionality constants at postshock conditions and correlating these values as a function of the gas composition and the product of freestream velocity and shock angle. The resulting equations for the proportionality constants in terms of velocity and gas composition and the corresponding simple realtions for enthalpy and temperature were incorporated into a flow field computational scheme. Comparison was good between the thermodynamic properties determined from these relations and those obtained by using a detailed computer code to determine the properties. Thus, an appreciable savings in computer time was realized with no significant loss in accuracy.

  19. Gas Desorption Behavior of Graphite Anodes in Lithium Ion Secondary Batteries After Adsorption of Electrolytes

    Science.gov (United States)

    Watanabe, Toshinori; Nobuta, Yuji; Yamauchi, Yuji; Hino, Tomoaki; Kubota, Yoshihiro; Ohzeki, Katsutomo

    When it was soaked, more were desorbed In this study, gas desorption behaviors of graphite anode samples after various surface treatments and electrolyte solvent adsorption properties were investigated. The total amount of desorbed gases for the natural graphite samples increased after soaking in propylene carbonate, and increased even further with Raman R value, suggesting that surface defects act as an effective adsorption site for the electrolyte. These findings indicate that surface treatment such as a coating might be an effective remedy to reduce the amount of desorption gases in natural graphite samples. It was also found that the total amount of gas desorption largely decreased with the coating with polymer resin and subsequent heat treatment at 423 K for 12 hours in a medium of air. It is likely that the dominant gas species present in the natural graphite after the electrolyte soaking are dependent on the binding energy and the molecular structure of the electrolyte solvent.

  20. The calculation of transport properties in quantum liquids using the maximum entropy numerical analytic continuation method: application to liquid para-hydrogen.

    Science.gov (United States)

    Rabani, Eran; Reichman, David R; Krilov, Goran; Berne, Bruce J

    2002-02-05

    We present a method based on augmenting an exact relation between a frequency-dependent diffusion constant and the imaginary time velocity autocorrelation function, combined with the maximum entropy numerical analytic continuation approach to study transport properties in quantum liquids. The method is applied to the case of liquid para-hydrogen at two thermodynamic state points: a liquid near the triple point and a high-temperature liquid. Good agreement for the self-diffusion constant and for the real-time velocity autocorrelation function is obtained in comparison to experimental measurements and other theoretical predictions. Improvement of the methodology and future applications are discussed.

  1. Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata

    NARCIS (Netherlands)

    Boks, N.P.; Kaper, H.J.; Norde, W.; Busscher, H.J.; Mei, van der H.C.

    2008-01-01

    Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces. although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients

  2. Synthesis and properties of ZnO-HMD@ZnO-Fe/Cu core-shell as advanced material for hydrogen storage.

    Science.gov (United States)

    Bouazizi, N; Boudharaa, T; Bargougui, R; Vieillard, J; Ammar, S; Le Derf, F; Azzouz, A

    2017-04-01

    In this paper, a new synthetic strategy towards functionalized ZnO-HMD@ZnO-Fe/Cu core-shell using sol-gel process modified by chemical grafting of hexamethylenediamine (HMD) on the core and in-situ dispersion of Cu(0)/Fe(0) as metallic nanoparticles (M-NPs) on the shell. The as-prepared core-shell materials were fully characterized by transmission electron microscopy, X-ray powder diffractometry, diffuse reflectance and FT-IR spectrophotometery, photoluminescence, and complexes impedance spectroscopy measurements. The XRD patterns agreed with that of the ZnO typical wurtzite structure, indicating good crystallinity of ZnO-HMD@ZnO-Fe/Cu, with the presence of Fe(0) and Cu(0) phases. Hexamethylenediamine grafting and M-NPs insertion were highly activated and enhanced the core and shell interface by the physiochemical interaction. After functionalization, luminescence intensities and electrical properties of both core and core-shell nanoparticles are improved, indicating the effects of the surface groups on the charge transfer of ZnO-HMD@ZnO-Fe/Cu. The hydrogen capacity retention was depended strongly on the composition and structure of the obtained core-shell. Iron/Copper-loaded ZnO-HMD@ZnO materials exhibited the highest capacity for hydrogen storage. The excellent stability and performance of the ZnO-HMD@ZnO-Fe/Cu core-shell make it an efficient candidate for hydrogen storage. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Standardized Testing Program for Solid-State Hydrogen Storage Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Michael A. [Southwest Research Institute; Page, Richard A. [Southwest Research Institute

    2012-07-30

    established and qualified standards. Working with industry, academia, and the U.S. government, SwRI set out to develop an accepted set of evaluation standards and analytical methodologies. Critical measurements of hydrogen sorption properties in the Laboratory have been based on three analytical capabilities: 1) a high-pressure Sievert-type volumetric analyzer, modified to improve low-temperature isothermal analyses of physisorption materials and permit in situ mass spectroscopic analysis of the sample’s gas space; 2) a static, high-pressure thermogravimetric analyzer employing an advanced magnetic suspension electro-balance, glove-box containment, and capillary interface for in situ mass spectroscopic analysis of the sample’s gas space; and 3) a Laser-induced Thermal Desorption Mass Spectrometer (LTDMS) system for high thermal-resolution desorption and mechanistic analyses. The Laboratory has played an important role in down-selecting materials and systems that have emerged from the MCoEs.

  4. Water's Hydrogen Bond Strength

    CERN Document Server

    Chaplin, Martin

    2007-01-01

    Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperature...

  5. Reversible Hydrogen Storage in a LiBH 4 –C 60 Nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Patrick A.; Teprovich, Joseph A.; Peters, Brent; Wheeler, Joseph; Compton, Robert N.; Zidan, Ragaiy

    2013-11-07

    Reversible hydrogen storage in a LiBH4:C60 nanocomposite (70:30 wt. %) synthesized by solvent-assisted mixing has been demonstrated. During the solvent-assisted mixing and nanocomposite formation, a chemical reaction occurs in which the C60 cages are significantly modified by polymerization as well as by hydrogenation (fullerane formation) in the presence of LiBH{sub 4}. We have determined that two distinct hydrogen desorption events are observed upon rehydrogenation of the material, which are attributed to the reversible formation of a fullerane (C60Hx) as well as a LiBH4 species. This system is unique in that the carbon species (C60) actively participates in the hydrogen storage process which differs from the common practice of melt infiltration of high surface area carbon materials with LiBH4 (nanoconfinment effect). This nanocomposite demonstrated good reversible hydrogen storage properties as well as the ability to absorb hydrogen under mild conditions (pressures as low as 10 bar H2 or temperatures as low as 150°C). The nanocomposite was characterized by TGA-RGA, DSC, XRD, LDI-TOF-MS, FTIR, 1H NMR, and APPI MS.

  6. TEMPERATURE-PROGRAMMED DESORPTION: PRINCIPLES, INSTRUMENT DESIGN, AND DEMONSTRATION WITH NAALH4

    Energy Technology Data Exchange (ETDEWEB)

    Stowe, A; Ragaiy Zidan, R

    2006-11-07

    This article is a brief introduction to temperature-programmed desorption (TPD), an analytical technique devised to analyze, in this case, materials for their potential as hydrogen storage materials. The principles and requirements of TPD are explained and the different components of a generic TPD apparatus are described. The construction of a modified TPD instrument from commercially available components is reported together with the control and acquisition technique used to create a TPD spectrum. The chemical and instrumental parameters to be considered in a typical TPD experiment and the analytical utility of the technique are demonstrated by the dehydrogenation of titanium-doped NaAlH{sub 4} by means of thermally programmed desorption.

  7. Electron Stimulated Molecular Desorption of a NEG St 707 at Room Temperature

    CERN Document Server

    Le Pimpec, F; Laurent, Jean Michel

    2001-01-01

    Electron stimulated molecular desorption (ESD) from a NEG St 707 (SAES GettersTM) sample after conditioning and after saturation with isotopic carbon monoxide2,13C18O, has been studied on a laboratory setup. Measurements were performed using an electron beam of 300 eV kinetic energy, with an average electron intensity of 1.6 1015 electrons s-1. The electrons were impinging on the 15 cm2 target surface at perpendicular incidence. It is found that the desorption yields h (molecules/electron) of the characteristic gases in an UHV system (hydrogen, methane, water, carbon monoxide, carbon dioxide) for a fully activated NEG as well as for a NEG fully saturated with 13C18O are lower than for OFHC copper baked at 120oC. A small fraction only of the gas which is required to saturate the getter surface can be re-desorbed and thus appears to be accessible to ESD.

  8. Sonochemical-driven ultrafast facile synthesis of SnO2 nanoparticles: Growth mechanism structural electrical and hydrogen gas sensing properties.

    Science.gov (United States)

    Ullah, Hafeez; Khan, Ibrahim; Yamani, Zain H; Qurashi, Ahsanulhaq

    2017-01-01

    Synthesis of SnO2 nanoparticles have been successfully accomplished moderately at lower temperature by facile, rapid, efficient and mild ultrasonic irradiation method. The as-grown SnO2 nanoparticles are investigated by various characterization techniques in terms of structural, optical, electrical and gas sensing properties. XRD investigation has shown that the SnO2 nanoparticles materials exhibit single rutile crystal phase with high crystallinity. FESEM studies showed uniform and monodisperse morphology of SnO2 nanoparticles. The chemical composition of SnO2 was systematically studied by EDX measurements. Additional confirmation of three Raman shifts (432, 630, 772cm(-1)) indicated the characteristic properties of the rutile phase of the as-grown SnO2 nanoparticles. The optical properties of SnO2 nanoparticles were examined by DRS, and the electronic band gap of SnO2 nanoparticles were around 3.6eV. Electrical properties of the SnO2 nanoparticles measured at various temperatures have shown the semiconducting properties. Surface area and pore size of synthesized nanoparticles were analyzed from BET. It has been revealed that SnO2 nanoparticles have surface area is 47.8574m(2)/g and the pore size is 10.5nm. Moreover, hydrogen gas sensor made of SnO2 nanoparticles showed good sensitivity and faster response for the hydrogen gas. This method is template-less and surfactant-free which circumvents rigorous reaction work-up for the former removal, reaction temperature and reaction time compared to hydrothermal synthesis and pertinent to many other oxide materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. New vistas in the determination of hydrogen in aerospace engine metal alloys

    Science.gov (United States)

    Danford, M. D.

    1986-01-01

    The application of diffusion theory to the analysis of hydrogen desorption data has been studied. From these analyses, important information concerning hydrogen solubilities and the nature of the hydrogen distributions in the metal has been obtained. Two nickel base alloys, Rene' 41 and Waspaloy, and one ferrous alloy, 4340 steel, were studied in this work. For the nickel base alloys, it was found that the hydrogen distributions after electrolytic charging conformed closely to those which would be predicted by diffusion theory. The hydrogen distributions in electrolytically charged 4340 steel, on the other hand, were essentially uniform in nature, which would not be predicted by diffusion theory. Finally, it has been found that the hydrogen desorption is completely explained by the nature of the hydrogen distribution in the metal, and that the 'fast' hydrogen is not due to surface and subsurface hydride formation, as was originally proposed.

  10. Catalytic Hydrogenation of CO2 to Methanol: Study of Synergistic Effect on Adsorption Properties of CO2 and H2 in CuO/ZnO/ZrO2 System

    Directory of Open Access Journals (Sweden)

    Chunjie Huang

    2015-11-01

    Full Text Available A series of CuO/ZnO/ZrO2 (CZZ catalysts with different CuO/ZnO weight ratios have been synthesized by citrate method and tested in the catalytic hydrogenation of CO2 to methanol. Experimental results showed that the catalyst with the lowest CuO/ZnO weight ratio of 2/7 exhibited the best catalytic performance with a CO2 conversion of 32.9%, 45.8% methanol selectivity, and a process delivery of 193.9 gMeOH·kgcat−1·h−1. A synergetic effect is found by systematic temperature-programmed-desorption (TPD studies. Comparing with single and di-component systems, the interaction via different components in a CZZ system provides additional active sites to adsorb more H2 and CO2 in the low temperature range, resulting in higher weight time yield (WTY of methanol.

  11. The cooling effect by adsorption-desorption cycles

    Directory of Open Access Journals (Sweden)

    Wolak Eliza

    2017-01-01

    Full Text Available Adsorption appliances may turn out to be an alternative to compression-type refrigerators. The adsorption refrigeration machine may be driven by a low-grade heat source, especially solar energy. Solar adsorption cooling systems are environment-friendly and have zero ozone depletion potential. Therefore, the adsorption refrigeration is one kind of energy saving refrigeration methods. The merits of the adsorption refrigeration systems will be more significant especially when it is used in vehicles (automobiles, ships and locomotives, to preserve food and medicines and in air-conditioning. The paper presents the advantages and disadvantages as well as the evolution of the technology of adsorptive refrigeration systems. The methods of improving of adsorption refrigeration systems through improvements in adsorbents properties, use of advanced cycles and hybrid systems is also presented. Possible applications and perspectives for development of adsorption cooling systems are also analyzed. The paper describes a test stand of the adsorption-desorption refrigeration. The present investigations have been carried out utilizing the activated carbon granules as an adsorbent and methanol as an adsorbate. The paper demonstrates the measurement of temperature changes in the adsorbent bed and condenser during adsorption-desorption cycles.

  12. Moisture adsorption and desorption behavior of sludge powder.

    Science.gov (United States)

    Freire, F B; Bentes Freire, F; Pires, E C; Freire, J T

    2007-11-01

    In this work, the moisture adsorption and desorption isotherms were determined with the aim of defining the range of moisture content for storage of sludge powder. Equilibrium moisture content provides the basis for information not only on how much water has been taken out of a system but also on how fast drying is taking place (drying rate). Once the drying process is accomplished, the main concern rests on the storage of the dried final product. Still, the equilibrium moisture content is valuable information in that it has a major effect on the product physical and chemical properties. The present work also addresses the problem of selecting the best fit for equilibrium moisture content of sludge powder out of six well-known correlations for moisture sorption isotherms of solids: Henderson, Henderson-Thompson, Chung-Pfost, Chen-Clayton, Modified Halsey and Oswin. The equilibrium moisture content was determined by the static method (saturated salt solutions), in which the atmosphere surrounding the product is in equilibrium with the product without mechanical movement of the air or the product. Experiments were carried out under isothermal conditions at 20 and 40 degrees C. By calculating the regression coefficient, the residuals and the bias measure of Box for the equilibrium moisture content, the study showed that the Oswin Model was the most suitable. The range enclosed within the adsorption isotherm at 40 degrees C and the desorption isotherm at 20 degrees C defines the moisture extremes for storage in most tropical areas of the world.

  13. Thermodynamics of the CO2–Absorption/Desorption Section in the Integrated Gasifying Combined Cycle — I. modeling

    Directory of Open Access Journals (Sweden)

    Jaroslav KOZACZKA

    2012-06-01

    Full Text Available The carbon dioxide absorption/desorption unit of the Integrated Gasifying Combined Cycle has been detailed described to formulate appropriate model equations for the processes, suitable for further thermodynamic analyzes. There are two principal technologies of the CO2–removing section, namely the absorption with the following expanding desorption process, and the absorption with the following classical plates (or packing desorption one. The physics of thermodynamic properties of the water/carbon dioxide solution have been presented thoroughly using hitherto literature data. The Henry's Law has been emphasized as the base for further thermodynamic analyzes. The numerical results of appropriate absorption/desorption units have been compiled presuming fundamental relations, which are also presented. They should be the base for their thermodynamic analyzes.

  14. X-ray and Hydrogen-bonding Properties of 1-((1H-benzotriazol-1-ylmethylnaphthalen-2-ol

    Directory of Open Access Journals (Sweden)

    Jaime Ríos-Motta

    2009-03-01

    Full Text Available The solid state structure of 1-((1H-benzotriazol-1-ylmethylnaphthalen-2-ol, C17H13N3O, shows that this Mannich base crystallizes forming intermolecular N···HO hydrogen bonds, rather than intramolecular ones. Factors contributing to this choice of hydrogen-bonding mode are discussed. The compound crystallizes in the monoclinic system, P21/c space group, with lattice constants: a = 11.7934(9 Å, b = 14.3002(14 Å, c = 8.4444(8 Å, β = 106.243(5 deg, V = 1367.3(2 Å3, Z = 4, F(000 = 576, R1 = 6.96%, wR2 = 11.4%.

  15. Effect of particle size and microstructure on the hydrogen storage property in a V-Ti-Cr solid solution system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hanjung; Yoo, Jeong-Hyun; Roh, Ki-Min; Suh, Chang-Yul; Kim, Won-Baek [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Cho, Sung-Wook, E-mail: cho@kigam.re.kr [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer V-Ti-Cr nano-particles were prepared via the electric explosion of wire. Black-Right-Pointing-Pointer Two kinds of particles with different size were formed. Black-Right-Pointing-Pointer Hydrogen storage capacity of nano-particles decreased due to increased surface area. Black-Right-Pointing-Pointer Plateau pressure was higher in the particle with smaller lattice parameter. Black-Right-Pointing-Pointer Hysteresis in P-C isotherm was larger in the particle with lower strain. - Abstract: Nano-particles of V-Ti and V-Ti-Cr alloys with a BCC (Body Centered Cubic) structure were prepared via the EEW (electric explosion of wire) method. However, due to the formation of chromium oxide (CrO{sub 0.87}) and/or vanadium oxide (V{sub 16}O{sub 3}) during the explosion, the exploded particles were deficient in Cr and V content, contrary to the anticipated composition, and micro-particles also formed in addition to the nano-particles. The hydrogen storage capacity of the exploded particles decreased compared to that of mechanically crushed particles from ingots, because the number of interstitial sites for hydrogen in the lattice was reduced due to the increased surface area and also because the BCC phase decreased as a result of the formation of oxide phases. As the lattice parameters of the alloys became small, the plateau pressure in the P-C isotherm increased because it was more difficult for hydrogen to diffuse through the lattice. It was also found that the strain induced by adding other elements in the V lattice reduced the hysteresis in the P-C isotherm.

  16. Thermomechanical properties of zirconium tungstate/hydrogenated nitrile butadiene rubber (HNBR) composites for low-temperature applications

    OpenAIRE

    Akulichev, Anton G.; Alcock, Ben; Tiwari, Avinash; Echtermeyer, Andreas T.

    2017-01-01

    Rubber compounds for pressure sealing application typically have inferior dimensional stability with temperature fluctuations compared with their steel counterparts. This effect may result in seal leakage failures when subjected to decreases in temperature. Composites of hydrogenated nitrile butadiene rubber (HNBR) and zirconium tungstate as a negative thermal expansion filler were prepared in order to control the thermal expansivity of the material. The amount of zirconium tungstate (ZrW2O8)...

  17. Syntheses, Crystal Structures, Magnetic Behaviours, and Thermal Properties of Three Hydrogen-Bonding Networks Containing Dicyanamide and 4-Hydroxypyridine

    Directory of Open Access Journals (Sweden)

    Lingling Zheng

    2013-01-01

    Full Text Available Three new dicyanamide-bridged polymeric complexes of {[Mn(dca2(L2]·2H2O}n (1, {[Cd(dca2(L2]·2H2O}n (2, and {[Co(dca2(L2]2(L}n (3 (dca = dicyanamide, L = pyridinium-4-olate have been synthesized and structurally characterized. In the three compounds, the protons of hydroxyl groups of 4-hydroxypyridine transfer to pyridyl nitrogen atoms. Compounds 1 and 2 are isomorphous forming one-dimensional [M(dca2(L2]n chains where metals are connected by double dca anions. These one-dimensional chains are extended into two-dimensional layers through weak C–H⋯N hydrogen bonds. Further, these layers are assembled into a three-dimensional supramolecular network through N–H⋯O, O–H⋯O hydrogen bonds. Complex 3 is a coordination layer of (4, 4 topology with octahedral metal centers linked by four single μ1,5-bridges. These layers are interlocked by N–H⋯O, O–H⋯O hydrogen bonds from coordinated water molecules and free L molecules, which leads to a three-dimensional supramolecular architecture. The variable temperature magnetic susceptibilities measurement of compounds 1 and 3 shows the existence of weak antiferromagnetic interactions between the metal centers. The thermogravimetric analyses of the compounds 1–3 are also discussed.

  18. Hydrogen-induced changes in the crystalline structure and mechanical properties of a Zn-Al eutectoid alloy rapidly solidified

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval Jimenez, Alberto; Iturbe Garcia, Jose Luis [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: alberto.sandoval@inin.gob.mx; asandovalj@correo.unam.mx; Negrete Sanchez, Jesus [Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico); Torres Villasenor, Gabriel [Instituto de Investigaciones en Materiales, UNAM, Mexico D.F. (Mexico)

    2009-09-15

    Ribbon fractions of a zinc-aluminum eutectoid (Zn40.8Al%at.) alloy, obtained by rapid solidification using melt spinning technique, were submitted to a thermo-hydrogenation process by periods of 1, 6, 18, 24, 30, and 48 hours, to 200 degrees Celsius and 20 atmospheres. Thermo-hydrogenated samples were analyzed by transmission electron microscopy (TEM). Hydrogen-induced changes were produced, such as microstructure refining, development of crystalline defects, microhardness changes and modification of stable crystalline structures to {alpha}R meta-stable phase at room temperature. [Spanish] Fracciones de tiras de una aleacion eutectoide de zinc-aluminio (Zn40.8Al%at.), obtenidas mediante solidificacion rapida usando la tecnica de melt spinning, se sometieron a un proceso de termohidrogenacion por periodos de 1, 6, 18, 24, 30 y 48 horas, a 200 grados centigrados y 20 atmosferas. Las muestras termohidrogenadas se analizaron por microscopia electronica de transmision (MET). Se produjeron cambios inducidos por hidrogeno, tales como la refinacion de la microestructura, el desarrollo de defectos cristalinos, cambios de microdureza y modificacion de las estructuras cristalinas estables a fase metaestable {alpha}R a temperatura ambiente.

  19. Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

    Science.gov (United States)

    Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

    2011-09-01

    The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

  20. Hydrogen treatment-improved uniform deposition of Ag nanoparticles on ZnO nanorod arrays and their visible-light photocatalytic and surface-enhanced Raman scattering properties.

    Science.gov (United States)

    Lin, Sio-Le; Hsu, Kai-Chih; Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2013-07-16

    ZnO nanorod arrays were synthesized by chemical bath deposition. After heat treatment in hydrogen or air, Ag nanoparticles were deposited on ZnO nanorod arrays by photo-reduction method. The size of Ag nanoparticles as well as the surface morphology, structure, composition, and optical property of ZnO nanorod arrays before and after the deposition of Ag nanoparticles were characterized by SEM, XRD, EDS, and UV/VIS/NIR spectrophotometer. As compared to the samples with heat treatment in air or without heat treatment, the ZnO nanorod arrays after heat treatment in hydrogen allowed Ag nanoparticles to be deposited more uniformly, densely, and numerously. Also, they exhibited higher efficiency for the visible light-driven photocatalytic degradation of Rhodamine 6G (R6G) dye. The effects of the amount of Ag nanoparticles, initial dye concentration, and temperature on the photocatalytic degradation efficiency were investigated. Furthermore, they also exhibited better surface-enhanced Raman scattering property for the detection of R6G dyes.

  1. Comparing the rates of absorption and weight loss during a desorption test using near infrared spectroscopy.

    Science.gov (United States)

    Qassem, M; Kyriacou, P A

    2013-05-01

    The importance of determining skin hydration has over the years prompt the development of many instruments and methods, specifically designed to assess this parameter or water contents especially in the stratum corneum, and have greatly matured to suit different anatomical sites and measure multiple attributes. Of those, Near Infrared Spectroscopy (NIRS) has gained wide interest as a precise, safe, fast and noninvasive technique for determining skin hydration due to its high sensitivity to hydrogen bonding and ability to measure the amount of water in skin directly using the intensities of overtone and combination bands of OH and HOH water bonds occurring in the NIR region, that are good indicators of the state of skin hydration. This paper reports near infrared spectrophotometric measurements using a highly sophisticated spectrophotometer in the region of 1000-2500 nm to study the water uptake and dehydration properties of skin in vitro using samples of porcine skin. Initial results of pure liquid water and skin samples have clearly displayed the prominent bands associated with water content, and desorption tests have been able to verify changes in these bands associated with water content, although a clear correlation between the rates of weight loss and absorbance loss at various hydration periods has not yet been established. These preliminary results are expected to further explain the relationship between water and skin, and its role within, in hope to aid the future development of a portable instrument based on near infrared spectroscopy that would be capable of directly measuring skin hydration and/or water content in a fast and noninvasive manner. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  2. Nanostructures from hydrogen implantation of metals.

    Energy Technology Data Exchange (ETDEWEB)

    McWatters, Bruce Ray (Sandia National Laboratories, Albuquerque, NM); Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2009-09-01

    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  3. Hydrogen in the Methanol Production Process

    Science.gov (United States)

    Kralj, Anita Kovac; Glavic, Peter

    2006-01-01

    Hydrogen is a very important industrial gas in chemical processes. It is very volatile; therefore, it can escape from the process units and its mass balance is not always correct. In many industrial processes where hydrogen is reacted, kinetics are often related to hydrogen pressure. The right thermodynamic properties of hydrogen can be found for…

  4. Hydrogen in all its states: from solid to gas and liquid; L'hydrogene dans tous ses etats: du solide au gaz en passant par le liquide

    Energy Technology Data Exchange (ETDEWEB)

    Latroche, M.; Joubert, J.M.; Cuevas, F.; Paul-Boncour, V.; Percheron-Guegan, A. [Institut de Chimie et des Materiaux Paris-Est, Chimie Metallurgique des Terres Rares (CMTR-ICMPE-UMR 7182), CNRS, 94 - Thiais (France)

    2007-07-01

    Hydrogen is considered as one of the future energy vector. Several means of hydrogen storage are presented here: physical solutions (compression, liquefaction) and chemical solutions (adsorption in porous solids and absorption in chemical hydrides). Each of these means presents advantages and disadvantages according to economical, energetic, specific capacity, safety and sorption/desorption kinetics criteria. (O.M.)

  5. In situ trace detection of peroxide explosives by desorption electrospray ionization and desorption atmospheric pressure chemical ionization.

    Science.gov (United States)

    Cotte-Rodríguez, Ismael; Hernandez-Soto, Heriberto; Chen, Hao; Cooks, R Graham

    2008-03-01

    Desorption electrospray ionization (DESI) mass spectrometry is used for the rapid (process triggered by an unusual homolytic cleavage of the peroxide bond, forming a distonic ion. This is followed by elimination of a fragment of 30 mass units, shown to be the expected neutral molecule, formaldehyde, in the case of HMTD, but shown by isotopic labeling experiments to be ethane in the cases of TATP and TrATrP. Density functional theory (DFT) calculations support the suggested fragmentation mechanisms for the complexes. Binding energies of Na+ of 40.2 and 33.1 kcal/mol were calculated for TATP-Na(+) and HMTD-Na(+) complexes, suggesting a strong interaction between the peroxide groups and the sodium ion. Increased selectivity is obtained either by MS/MS or by doping the spray solvent with additives that produce the lithium and potassium complexes of TATP, HMTD, and TrATrP. Addition of dopants into the solvent spray increased the signal intensity by an order of magnitude. When pure alcohol or aqueous hydrogen peroxide was used as the spray solvent, the (HMTD + Na)+ complex was able to bind a molecule of alcohol (methanol or ethanol) or hydrogen peroxide, providing additional characteristic ions to increase the selectivity of analysis. DESI also allowed the rapid detection of peroxide explosives in complex matrixes such as diesel fuel and lubricants using single or multiple cation additives (Na(+), K(+), and Li(+), and NH4(+)) in the spray solvent. Low-nanogram detection limits were achieved for HMTD, TrATrP, and TATP in these complex matrixes. The DESI response was linear over 3 orders of magnitude for HMTD and TATP on paper surfaces (1-5000 ng), and quantification of both peroxide explosives from paper gave precisions (RSD) of less than 3%. The use of pure water and compressed air as the DESI spray solution and nebulizing gas, respectively, showed similar ionization efficiencies to those obtained using methanol/water mixtures and nitrogen gas (the typical choices). An

  6. Effect of the Metal Hydride Tank Structure on the Reaction Heat Recovery for the Totalized Hydrogen Energy Utilization System

    National Research Council Canada - National Science Library

    Maeda, Tetsuhiko; Nakano, Akihiro; Ito, Hiroshi; Motyka, Theodore; Perez-Berrios, Jose M; Greenway, Scott

    2013-01-01

    .... In this paper, a metal hydride tank (MHT) is chosen as hydrogen storage. In the MHT, the heating and cooling from adsorption/desorption processes is used to produced heated and chilled water for building ventilation systems...

  7. Experimental factors controlling analyte ion generation in laser desorption/ionization mass spectrometry on porous silicon.

    Science.gov (United States)

    Kruse, R A; Li, X; Bohn, P W; Sweedler, J V

    2001-08-01

    Desorption/ionization on porous silicon (DIOS) is a relatively new laser desorption/ionization technique for the direct mass spectrometric analysis of a wide variety of samples without the requirement of a matrix. Porous silicon substrates were fabricated using the recently developed nonelectrochemical H2O2-metal-HF etching as a versatile platform for investigating the effects of morphology and physical properties of porous silicon on DIOS-MS performance. In addition, laser wavelength, mode of ion detection, pH, and solvent contributions to the desorption/ionization process were studied. Other porous substrates such as GaAs and GaN, with similar surface characteristics but differing in thermal and optical properties from porous silicon, allowed the roles of surface area, optical absorption, and thermal conductivities in the desorption/ionization process to be investigated. Among the porous semiconductors studied, only porous silicon has the combination of large surface area, optical absorption, and thermal conductivity required for efficient analyte ion generation under the conditions studied. In addition to these substrate-related factors, surface wetting, determined by the interaction of deposition solvent with the surface, and charge state of the peptide were found to be important in determining ion generation efficiency.

  8. Characterizing particle-scale equilibrium adsorption and kinetics of uranium(VI) desorption from U-contaminated sediments

    Science.gov (United States)

    Stoliker, Deborah L.; Liu, Chongxuan; Kent, Douglas B.; Zachara, John M.

    2013-01-01

    Rates of U(VI) release from individual dry-sieved size fractions of a field-aggregated, field-contaminated composite sediment from the seasonally saturated lower vadose zone of the Hanford 300-Area were examined in flow-through reactors to maintain quasi-constant chemical conditions. The principal source of variability in equilibrium U(VI) adsorption properties of the various size fractions was the impact of variable chemistry on adsorption. This source of variability was represented using surface complexation models (SCMs) with different stoichiometric coefficients with respect to hydrogen ion and carbonate concentrations for the different size fractions. A reactive transport model incorporating equilibrium expressions for cation exchange and calcite dissolution, along with rate expressions for aerobic respiration and silica dissolution, described the temporal evolution of solute concentrations observed during the flow-through reactor experiments. Kinetic U(VI) desorption was well described using a multirate SCM with an assumed lognormal distribution for the mass-transfer rate coefficients. The estimated mean and standard deviation of the rate coefficients were the same for all distribution of mass-transfer rate coefficients, possibly caused by the abundance of microporous basaltic rock fragments.

  9. Assessing pesticide leaching and desorption in soils with different agricultural activities from Argentina (Pampa and Patagonia).

    Science.gov (United States)

    Gonzalez, Mariana; Miglioranza, Karina S B; Aizpún, Julia E; Isla, Federico I; Peña, Aránzazu

    2010-09-01

    Pesticide distribution in the soil profile depends on soil and pesticide properties as well as on the composition of irrigation water. Water containing surfactants, acids or solvents, may alter pesticide desorption from soil. The distribution of organochlorine pesticides (OCPs) in two Argentinean agricultural areas, Pampa and Patagonia, was evaluated. Furthermore, pesticide desorption from aged and freshly spiked soils was performed by the batch technique, using solutions of sodium oxalate and citrate, dissolved organic carbon (DOC), wastewater and surfactants. Patagonian soil showed the highest OCP levels (46.5-38.1 μg g(-1) OC) from 0 to 30 cm depth and the predominance of p,p'-DDE residues reflected an extensive and past use of DDT. Pampean soil with lower levels (0.039-0.07 μg g(-1) OC) was mainly polluted by the currently used insecticide endosulfan. Sodium citrate and oxalate, at levels usually exuded by plant roots, effectively enhanced desorption of p,p'-DDT, p,p'-DDE and α-cypermethrin, while no effects were observed for α-endosulfan and endosulfan sulfate. The non-ionic surfactant Tween 80 behaved similarly to the acids, whereas the anionic sodium dodecyl sulfate enhanced desorption of all pesticides. Increased desorption of the hydrophobic pesticides also occurred when DOC from humic acids but not from sewage sludge or wastewater were used. Soil profile distribution of pesticides was in accordance with results from desorption studies. Data suggest pesticide leaching in Pampean and Patagonian soils, with risk of endosulfan to reach groundwater and that some organic components of wastewaters may enhance the solubilisation and leaching of recalcitrant compounds such as p,p'-DDT and p,p'-DDE. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Effects of External Hydrogen on Hydrogen Transportation and Distribution Around the Fatigue Crack Tip in Type 304 Stainless Steel

    Science.gov (United States)

    Chen, Xingyang; Zhou, Chengshuang; Cai, Xiao; Zheng, Jinyang; Zhang, Lin

    2017-10-01

    The effects of external hydrogen on hydrogen transportation and distribution around the fatigue crack tip in type 304 stainless steel were investigated by using hydrogen microprint technique (HMT) and thermal desorption spectrometry. HMT results show that some silver particles induced by hydrogen release are located near the fatigue crack and more silver particles are concentrated around the crack tip, which indicates that hydrogen accumulates in the vicinity of the crack tip during the crack growth in hydrogen gas environment. Along with the crack propagation, strain-induced α' martensite forms around the crack tip and promotes hydrogen invasion into the matrix, which will cause the crack initiation and propagation at the austenite/ α' martensite interface. In addition, the hydrogen content in the vicinity of the crack tip is higher than that at the crack edge far away from the crack tip, which is related to the stress state and strain-induced α' martensite.

  11. [The action of nitrite-anions and hydrogen peroxide on surface properties of the smooth muscle plasmatic membrane].

    Science.gov (United States)

    Danylovych, Iu V; Karakhim, S O

    2008-01-01

    In the presence of vesicular preparations of sarcolemma (near 70% reverse cytoplasmic sideways inward) fluorescence of ANS--1-(fenilamino)-8-naftylamine--rises more than 10 times. In the conditions of increase of concentration of sodium nitrite and hydrogen peroxide from 1 to 5 microM the probe fluorescence diminishes. Extinguishing of ANS fluorescence under the action of nitrite anions can be explained by chemical modification of the positively charged superficial groups (amino- and sulfhydrile). It will result in the decrease of amounts of local "+"-charges on a membrane, proper decrease of fastening ANS with a membrane and fluorescence extinguishing. H2O2 is able to oxidize superficial -SH-groups which carry a partial positive charge. Consequently a decrease of general amount of fixed "+" charges on a membrane, diminishing of ANS fastening with sarcolemma and the proper fluorescence extinguishing takes place. Probed and calculated by the method "ion beats" superficial closeness of charges of vesicular preparations makes 2.3 +/- 0.1 mC/m2. At the action of 50 microM sodium nitrite and hydrogen peroxide it diminishes to 2.0 +/- 0.1 mC/m2 and 1.7 +/- 0.07 mC/m2 accordingly. The less effective action of NaNO2 can be determined by the influence of Na+ on the superficial field of membrane. With the purpose to confirm the previous suppositions we used the method of laser-correlation spectroscopy, that registered the mean value of hydrodynamic diameter (GD) of vesicules and their division by sizes. Middle GD makes in control 327 +/- 16 nm, and GD which is most often met in population--291 +/- 11 nm. Adding of nitrite anions to the system in a growing concentration results in the substantial decline of GD of both all the membrane population and of plasma vesicules. Analogous results are obtained in the case of H2O2. In the presence of specific modifiers of sulfhydrile- and aminogroup of membrane surface (DTT and TNBS) the decline of GD under the action of nitrite anions

  12. Thermodynamic and dynamic dielectric properties of one-dimensional hydrogen bonded ferroelectric of PbHPO4-type

    Directory of Open Access Journals (Sweden)

    I.R. Zachek

    2014-12-01

    Full Text Available Within the modified model of proton ordering of one-dimensional ferroelectric having hydrogen bonds of PbHPO4-type, their thermodynamic and dynamic characteristics are studied and calculated taking into account the linear (by crystal deformations ϵi (i=1,3 and ϵ4 contributions into the energy of a proton system but without taking into account the tunneling in the two-particle cluster approximation. There has been obtained a good quantitative description of the temperature dependence of polarization, static dielectric permittivity, heat capacity and frequency dependence of dynamic dielectric permittivity at different temperatures for PbHPO4 and PbHDO4 crystals.

  13. Ionization Mechanism of Matrix-Assisted Laser Desorption/Ionization

    Science.gov (United States)

    Lu, I.-Chung; Lee, Chuping; Lee, Yuan-Tseh; Ni, Chi-Kung

    2015-07-01

    In past studies, mistakes in determining the ionization mechanism in matrix-assisted laser desorption/ionization (MALDI) were made because an inappropriate ion-to-neutral ratio was used. The ion-to-neutral ratio of the analyte differs substantially from that of the matrix in MALDI. However, these ratios were not carefully distinguished in previous studies. We begin by describing the properties of ion-to-neutral ratios and reviews early experimental measurements. A discussion of the errors committed in previous theoretical studies and a comparison of recent experimental measurements follow. We then describe a thermal proton transfer model and demonstrate how the model appropriately describes ion-to-neutral ratios and the total ion intensity. Arguments raised to challenge thermal ionization are then discussed. We demonstrate how none of the arguments are valid before concluding that thermal proton transfer must play a crucial role in the ionization process of MALDI.

  14. Electronic and Optical Properties of Small Hydrogenated Silicon Quantum Dots Using Time-Dependent Density Functional Theory

    Directory of Open Access Journals (Sweden)

    Muhammad Mus-’ab Anas

    2015-01-01

    Full Text Available This paper presents a systematic study of the absorption spectrum of various sizes of small hydrogenated silicon quantum dots of quasi-spherical symmetry using the time-dependent density functional theory (TDDFT. In this study, real-time and real-space implementation of TDDFT involving full propagation of the time-dependent Kohn-Sham equations were used. The experimental results for SiH4 and Si5H12 showed good agreement with other earlier calculations and experimental data. Then these calculations were extended to study larger hydrogenated silicon quantum dots with diameter up to 1.6 nm. It was found that, for small quantum dots, the absorption spectrum is atomic-like while, for relatively larger (1.6 nm structure, it shows bulk-like behavior with continuous plateau with noticeable peak. This paper also studied the absorption coefficient of silicon quantum dots as a function of their size. Precisely, the dependence of dot size on the absorption threshold is elucidated. It was found that the silicon quantum dots exhibit direct transition of electron from HOMO to LUMO states; hence this theoretical contribution can be very valuable in discerning the microscopic processes for the future realization of optoelectronic devices.

  15. The effects of martensite morphology on mechanical properties, corrosion behavior and hydrogen assisted cracking in A516 grade steel

    Science.gov (United States)

    Shahzad, M.; Tayyaba, Q.; Manzoor, T.; ud-din, Rafi; Subhani, T.; Qureshi, A. H.

    2018-01-01

    A low carbon A516 steel (0.2% C) having 0.9% Mn content has been annealed at 760 °C with predominantly austenite and martensite input structure. This treatment lead to a dual phase (DP) ferrite–martensite microstructures with 50% martensite volume fraction in two morphologies, i.e. bulk martensite (BM) and fibrous martensite (FM) respectively. The ferrite–martensite DP steels exhibits much higher strength (∼2 times) than ferrite–pearlite (FP) steel albeit with lower elongation (50%). The martensite morphology does not affect the uniform elongation but FM morphology exhibits higher strain to fracture. However, the corrosion rate is effected by the fraction of interfaces rather than the type of constituent phase. The BM condition with minimum interfaces has the least corrosion rate in weak acidic solution. The DP steels are more disposed to hydrogen embrittlement than FP steel. This phenomena causes a lowering of flow stress and strain fracture, the former is more progressive with rise in temperature than the latter. The crack nucleation is directly related to the corrosion rate, however despite twofold higher corrosion rate in BM condition, the extent of hydrogen embrittlement in both morphologies is similar because of the connected ferrite–martensite boundaries in BM morphology.

  16. Hydrothermal Synthesis and Structural Characterization of NiO/SnO2 Composites and Hydrogen Sensing Properties

    Directory of Open Access Journals (Sweden)

    Chao Wei

    2015-01-01

    Full Text Available Pure SnO2 and NiO doped SnO2 nanostructures were successfully synthesized via a simple and environment-friendly hydrothermal method. X-ray powder diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDS, and X-ray photoelectron spectra (XPS were used to investigate the crystalline structures, surface morphologies and microstructures, and element components and their valences of the as-synthesized samples. Furthermore, planar chemical gas sensors based on the synthesized pure SnO2 and NiO/SnO2 composites were fabricated and their sensing performances to hydrogen, an important fault characteristic gas dissolved in power transformer oil, were investigated in detail. Gas sensing experiments indicate that the NiO/SnO2 composites showed much higher gas response and lower working temperature than those of pure SnO2, which could be ascribed to the formation of p-n heterojunctions between p-type NiO and n-type SnO2. These results demonstrate that the as-synthesized NiO/SnO2 composites a promising hydrogen sensing material.

  17. Estimation of individual binding energies in some dimers involving multiple hydrogen bonds using topological properties of electron charge density

    Science.gov (United States)

    Ebrahimi, A.; Habibi Khorassani, S. M.; Delarami, H.

    2009-11-01

    Individual hydrogen bond (HB) energies have been estimated in several systems involving multiple HBs such as adenine-thymine and guanine-cytosine using electron charge densities calculated at X⋯H hydrogen bond critical points (HBCPs) by atoms in molecules (AIM) method at B3LYP/6-311++G ∗∗ and MP2/6-311++G ∗∗ levels. A symmetrical system with two identical H bonds has been selected to search for simple relations between ρHBCP and individual EHB. Correlation coefficient between EHB and ρHBCP in the base of linear, quadratic, and exponential equations are acceptable and equal to 0.95. The estimated individual binding energies EHB are in good agreement with the results of atom-replacement approach and natural bond orbital analysis (NBO). The EHB values estimated from ρ values at H⋯X BCP are in satisfactory agreement with the main geometrical parameter H⋯X. With respect to the obtained individual binding energies, the strength of a HB depends on the substituent and the cooperative effects of other HBs.

  18. ERDA. Technique for hydrogen content and depth profile in thin film metal hydride

    Energy Technology Data Exchange (ETDEWEB)

    Jain, I.P.; Jain, Ankur; Jain, Pragya [Rajasthan Univ., Jaipur (India). Centre for Non Conventional Energy Resources

    2010-07-01

    The use of thin films for hydrogen storage has become very important as the main process of absorption and desorption of hydrogen takes place on the surface of the material. The incorporation of hydrogen into thin film form is relatively new field of research and provides an opportunity to examine a number of unusual properties, which are not visible in the bulk hydrides. Considerable amount of work has been done in our laboratory to investigate hydrogen absorption mechanism in FeTi, LaNi, and MmNi{sub 4.5}Al{sub 0.5} thin film metal hydrides. Over the past few decades thin films are analyzed using ion beam analysis techniques where an energetic incident ion provides depth information on the basis of the energy lost by it and the creation of possible secondary particles in the sample. One of the most commonly used such techniques is Rutherford Backscattering (RBS) which makes use of {alpha} particles of few MeV energy and is based on the principle of elastic scattering. One of the main drawbacks of RBS is its poor sensitivity for light elements present in a heavier matrix. Hence hydrogen cannot be detected using RBS as backscattering of ions from hydrogen is not possible. The limitations of RBS are overcome by another technique, Elastic Recoil Detection Analysis (ERDA), in which the yield and energy of particle ejected out of thin film sample under swift heavy ion beam irradiation is detected giving the quantitative information concerning the depth distribution of light elements in a sample. In the present work ERDA technique is being presented with its principle, design, working and application for hydrogen content and depth profile in thin film hydride. (orig.)

  19. Hysteresis-free nanoplasmonic pd-au alloy hydrogen sensors

    DEFF Research Database (Denmark)

    Wadell, Carl; Nugroho, Ferry Anggoro Ardy; Lidström, Emil

    2015-01-01

    hydrogen sensors. By increasing the amount of Au in the alloy nanoparticles up to 25 atom %, we are able to suppress the hysteresis between hydrogen absorption and desorption, thereby increasing the sensor accuracy to below 5% throughout the investigated 1 mbar to 1 bar hydrogen pressure range. Furthermore......, we observe an 8-fold absolute sensitivity enhancement at low hydrogen pressures compared to sensors made of pure Pd, and an improved sensor response time to below one second within the 0-40 mbar pressure range, that is, below the flammability limit, by engineering the nanoparticle size....

  20. Alloying effect on the electronic structures of hydrogen storage compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yukawa, H.; Moringa, M.; Takahashi, Y. [Nagoya Univ. (Japan). Dept. of Mater. Sci. and Eng.

    1997-05-20

    The electronic structures of hydrogenated LaNi{sub 5} containing various 3d transition elements were investigated by the DV-X{alpha} molecular orbital method. The hydrogen atom was found to form a strong chemical bond with the Ni rather than the La atoms. The alloying modified the chemical bond strengths between atoms in a small metal octahedron containing a hydrogen atom at the center, resulting in the change in the hydrogen absorption and desorption characteristics of LaNi{sub 5} with alloying. (orig.) 7 refs.

  1. Technical and economic aspects of hydrogen storage in metal hydrides

    Science.gov (United States)

    Schmitt, R.

    1981-01-01

    The recovery of hydrogen from such metal hydrides as LiH, MgH2, TiH2, CaH2 and FeTiH compounds is studied, with the aim of evaluating the viability of the technique for the storage of hydrogen fuel. The pressure-temperature dependence of the reactions, enthalpies of formation, the kinetics of the hydrogen absorption and desorption, and the mechanical and chemical stability of the metal hydrides are taken into account in the evaluation. Economic aspects are considered. Development of portable metal hydride hydrogen storage reservoirs is also mentioned.

  2. Hydrogen Sorption Performance of Pure Magnesium during Continued Cycling

    DEFF Research Database (Denmark)

    Vigeholm, B.; Kjøller, John; Larsen, B.

    1983-01-01

    Preliminary investigations of the hydrogen absorption - desorption by commercially pure magnesium powder under continuous operation show little or no reduction in hydrogen capacity up to 70 cycles and high temperature exposure exceeding 1200 h. Absorption was studied at 260°–425°C and hydrogen...... of the powder into a highly porous, sintered agglomerate did not reduce the hydrogen capacity or the reaction rate. Although this change in structure caused no deterioration of the cycling performance a further development may not be acceptable. For observation over a much larger number of cyclings a fully...... automated, triple line cycling facility permitting simultaneous testing under different conditions has been constructed....

  3. Hydrogen Generator

    Science.gov (United States)

    1983-01-01

    A unit for producing hydrogen on site is used by a New Jersey Electric Company. The hydrogen is used as a coolant for the station's large generator; on-site production eliminates the need for weekly hydrogen deliveries. High purity hydrogen is generated by water electrolysis. The electrolyte is solid plastic and the control system is electronic. The technology was originally developed for the Gemini spacecraft.

  4. Impact of strain on electronic and transport properties of 6 nm hydrogenated germanane nano-ribbon channel double gate field effect transistor

    Science.gov (United States)

    Meher Abhinav, E.; Sundararaj, Anuraj; Gopalakrishnan, Chandrasekaran; Kasmir Raja, S. V.; Chokhra, Saurabh

    2017-11-01

    In this work, chair like fully hydrogenated germanane (CGeH) nano-ribbon 6 nm short channel double gate field effect transistor (DG-FET) has been modeled and the impact of strain on the I–V characteristics of CGeH channel has been examined. The bond lengths, binding and formation energies of various hydrogenated geometries of buckled germanane channel were calculated using local density approximation (LDA) with Perdew–Zunger (PZ) and generalized gradient approximation (GGA) with Perdew Burke Ernzerhof (PBE) parameterization. From four various geometries, chair like structure is found to be more stable compared to boat like obtuse, stiruup structure and table like structure. The bandgap versus width, bandgap versus strain characteristics and I–V characteristics had been analyzed at room temperature using density functional theory (DFT). Using self consistent calculation it was observed that the electronic properties of nano-ribbon is independent of length and band structure, but dependent on edge type, strain [Uni-axial (ε xx ), bi-axial (ε xx   =  ε yy )] and width of the ribbon. The strain engineered hydrogenated germanane (GeH) showed wide direct bandgap (2.3 eV) which could help to build low noise electronic devices that operates at high frequencies. The observed bi-axial compression has high impact on the device transport characteristics with peak to valley ratio (PVR) of 2.14 and 380% increase in peak current compared to pristine CGeH device. The observed strain in CGeH DG-FET could facilitate in designing novel multiple-logic memory devices due to multiple negative differential resistance (NDR) regions.

  5. Hydrogen attack - Influence of hydrogen sulfide. [on carbon steel

    Science.gov (United States)

    Eliezer, D.; Nelson, H. G.

    1978-01-01

    An experimental study is conducted on 12.5-mm-thick SAE 1020 steel (plain carbon steel) plate to assess hydrogen attack at room temperature after specimen exposure at 525 C to hydrogen and a blend of hydrogen sulfide and hydrogen at a pressure of 3.5 MN/sq m for exposure times up to 240 hr. The results are discussed in terms of tensile properties, fissure formation, and surface scales. It is shown that hydrogen attack from a high-purity hydrogen environment is severe, with the formation of numerous methane fissures and bubbles along with a significant reduction in the room-temperature tensile yield and ultimate strengths. However, no hydrogen attack is observed in the hydrogen/hydrogen sulfide blend environment, i.e. no fissure or bubble formation occurred and the room-temperature tensile properties remained unchanged. It is suggested that the observed porous discontinuous scale of FeS acts as a barrier to hydrogen entry, thus reducing its effective equilibrium solubility in the iron lattice. Therefore, hydrogen attack should not occur in pressure-vessel steels used in many coal gasification processes.

  6. Hydrogen adsorption and storage on Palladium - functionalized graphene with NH-dopant: A first principles calculation

    Science.gov (United States)

    Faye, Omar; Szpunar, Jerzy A.; Szpunar, Barbara; Beye, Aboubaker Chedikh

    2017-01-01

    We conducted a detailed theoretical investigation of the structural and electronic properties of single and double sided Pd-functionalized graphene and NH-doped Pd-functionalized graphene, which are shown to be efficient materials for hydrogen storage. Nitrene radical dopant was an effective addition required for enhancing the Pd binding on the graphene sheet as well as the storage of hydrogen. We found that up to eight H2 molecules could be adsorbed by double-sided Pd-functionalized graphene at 0 K with an average binding energy in the range 1.315-0.567 eVA gravimetric hydrogen density of 3.622 wt% was reached in the Pd-functionalized graphene on both sides. The binding mechanism of H2 molecules came not only the polarization mechanism between Pd and H atoms but also from the binding of the Pd atoms on the graphene sheet and the orbital hybridization. The most crucial part of our work is measuring the effect of nitrene radical on the H2 adsorption on Pd-functionalized graphene. Our calculations predicted that the addition of NH radicals on Pd-functionalized graphene enhance the binding of H2 molecules, which helps also to avoid the desorption of Pd(H2)n (n = 1-5) complexes from graphene sheet. Our results also predict Pd-functionalized NH-doped graphene is a potential hydrogen storage medium for on-board applications.

  7. The Synthesis and Structural Properties of Crystalline Silicon Quantum Dots upon Thermal Annealing of Hydrogenated Amorphous Si-Rich Silicon Carbide Films

    Science.gov (United States)

    Wen, Guozhi; Zeng, Xiangbin; Li, Xianghu

    2016-08-01

    Silicon quantum dots (QDs) embedded in non-stoichiometric hydrogenated silicon carbide (SiC:H) thin films have been successfully synthesized by plasma-enhanced chemical vapor deposition and post-annealing. The chemical composition analyses have been carried out by x-ray photoelectron spectroscopy (XPS). The bonding configurations have been deduced from Fourier transform infrared absorption measurements (FTIR). The evolution of microstructure with temperature has been characterized by glancing incident x-ray diffraction (XRD) and Raman diffraction spectroscopy. XPS and FTIR show that it is in Si-rich feature and there are a few hydrogenated silicon clusters in the as-grown sample. XRD and Raman diffraction spectroscopy show that it is in amorphous for the as-grown sample, while crystalline silicon QDs have been synthesized in the 900°C annealed sample. Silicon atoms precipitation from the SiC matrix or silicon phase transition from amorphous SiC is enhanced with annealing temperature increase. The average sizes of silicon QDs are about 5.1 nm and 5.6 nm, the number densities are as high as 1.7 × 1012 cm-2 and 3.2 × 1012 cm-2, and the crystalline volume fractions are about 58.3% and 61.3% for the 900°C and 1050°C annealed samples, respectively. These structural properties analyses provide an understanding about the synthesis of silicon QDs upon thermal annealing for applications in next generation optoelectronic and photovoltaic devices.

  8. Adsorption of molecular hydrogen on an ultrathin layer of Ni(111) hydride

    NARCIS (Netherlands)

    Shan, J. J.; Kleyn, A. W.; Juurlink, L. B. F.

    2009-01-01

    We have used high resolution electron energy loss spectroscopy and temperature-programmed desorption to study the interaction of atomic hydrogen with Ni(1 1 1). Our results agree mostly with previous reports. We find that exposing Ni(1 1 1) to atomic hydrogen below 90 K leads to a 125 K TPD feature

  9. Molecular structure, hydrogen bonding and spectroscopic properties of the complex of piperidine-4-carboxylic acid with chloroacetic acid

    Science.gov (United States)

    Komasa, A.; Katrusiak, A.; Szafran, M.; Barczyński, P.; Dega-Szafran, Z.

    2008-10-01

    Complex of piperidine-4-carboxylic acid with chloroacetic acid has been studied by X-ray diffraction, FTIR, Raman, 1H and 13C NMR spectroscopy and B3LYP/6-31G(d,p) calculations. In crystal the piperidine ring is protonated and adopts a chair conformation with the COOH group in the equatorial position. The COO - group of chloroacetate unit is engaged in three hydrogen bonds: O(1)-H(1)···O(3) of 2.604(2) Å, N(1)-H(12)···O(3) of 2.753(2) Å and N(1)-H(11)···O(4) of 2.760(2) Å. According to the B3LYP calculations the isolated complexes both in vacuum and H 2O solution have cyclic structures. In vacuum the molecules are connected by two H-bonds: the COOH group of chloroacetic acid is engaged with piperidine-4-carboxylic acid, one with the nitrogen atom, O(4)-H···N(1) of 2.658 Å and the second with carboxyl group, O(1)-H···O(3) of 2.860 Å. In water solution piperidine-4-carboxylic acid is protonated and forms two hydrogen bonds with the chloroacetate unit: N(1)-H···O(4) of 2.690 Å and O(1)-H···O(3) of 2.611 Å. Powder FTIR spectra of the complex and its deuterated analogue are consistent with the X-ray structure. Correlations between the experimental 1H and 13C chemical shifts of the complex investigated and the GIAO/B3LYP/6-31G(d,p) calculated magnetic isotropic shielding tensors ( σcalc) in vacuum and within the conductor-like screening continuum solvation model (COSMO) in H 2O, δexp = a + b σcalc, are reported.

  10. Hydrogenation Properties of Laves Phases LnMg2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb).

    Science.gov (United States)

    Werwein, Anton; Maaß, Florian; Dorsch, Leonhard Y; Janka, Oliver; Pöttgen, Rainer; Hansen, Thomas C; Kimpton, Justin; Kohlmann, Holger

    2017-12-18

    The hydrogenation properties of Laves phases LnMg2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb) were investigated by thermal analysis, X-ray, synchrotron, and neutron powder diffraction. At 14.0 MPa hydrogen gas pressure and 393 K, PrMg2 and NdMg2 take up hydrogen and form the colorless, ternary hydrides PrMg2H7 (P41212, a = 632.386(6) pm, c = 945.722(11) pm) and NdMg2H7 (P41212, a = 630.354(9) pm, c = 943.018(16) pm). The crystal structures were refined by the Rietveld method from neutron powder diffraction data on the deuterides (PrMg2D7, P41212, a = 630.56(2) pm, c = 943.27(3) pm; NdMg2D7, P41212, a = 628.15(2) pm, c = 940.32(3) pm) and shown to be isotypic to LaMg2D7. The LaMg2D7 type of hydrides decompose at 695 K (La), 684 K (Ce), 684 K (Pr), 672 K (Nd), and 639 K (Sm) to lanthanide hydrides and magnesium. The Laves phase EuMg2 forms a hydride EuMg2Hx of black color. Its crystal structure (P212121, a = 664.887(4) pm, b = 1136.993(7) pm, c = 1069.887(7) pm) is closely related to the hexagonal Laves phase (MgZn2 type) of the hydrogen-free parent intermetallic. GdMg2 and TbMg2 form hydrides GdMg2Hx with orthorhombic unit cells (a = 1282.7(4) pm, b = 572.5(2) pm, c = 881.7(2) pm) and TbMg2Hx (a = 617.8(3) pm, b = 1045.8(8) pm, c = 997.1(5) pm), presumably also with a distorted MgZn2 type of structure. CeMg2H7 and NdMg2H7 are paramagnetic with effective magnetic moments of 2.49(1) μB and 3.62(1) μB, respectively, in good agreement with the calculated magnetic moments of the free trivalent rare-earth cations (μcalc(Ce3+) = 2.54 μB; μcalc(Nd3+) = 3.62 μB).

  11. Liquid Organic Hydrogen Carriers (LOHCs): Toward a Hydrogen-free Hydrogen Economy.

    Science.gov (United States)

    Preuster, Patrick; Papp, Christian; Wasserscheid, Peter

    2017-01-17

    The need to drastically reduce CO 2 emissions will lead to the transformation of our current, carbon-based energy system to a more sustainable, renewable-based one. In this process, hydrogen will gain increasing importance as secondary energy vector. Energy storage requirements on the TWh scale (to bridge extended times of low wind and sun harvest) and global logistics of renewable energy equivalents will create additional driving forces toward a future hydrogen economy. However, the nature of hydrogen requires dedicated infrastructures, and this has prevented so far the introduction of elemental hydrogen into the energy sector to a large extent. Recent scientific and technological progress in handling hydrogen in chemically bound form as liquid organic hydrogen carrier (LOHC) supports the technological vision that a future hydrogen economy may work without handling large amounts of elemental hydrogen. LOHC systems are composed of pairs of hydrogen-lean and hydrogen-rich organic compounds that store hydrogen by repeated catalytic hydrogenation and dehydrogenation cycles. While hydrogen handling in the form of LOHCs allows for using the existing infrastructure for fuels, it also builds on the existing public confidence in dealing with liquid energy carriers. In contrast to hydrogen storage by hydrogenation of gases, such as CO 2 or N 2 , hydrogen release from LOHC systems produces pure hydrogen after condensation of the high-boiling carrier compounds. This Account highlights the current state-of-the-art in hydrogen storage using LOHC systems. It first introduces fundamental aspects of a future hydrogen economy and derives therefrom requirements for suitable LOHC compounds. Molecular structures that have been successfully applied in the literature are presented, and their property profiles are discussed. Fundamental and applied aspects of the involved hydrogenation and dehydrogenation catalysis are discussed, characteristic differences for the catalytic conversion of

  12. Optical and passivating properties of hydrogenated amorphous silicon nitride deposited by plasma enhanced chemical vapour deposition for application on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wight, Daniel Nilsen

    2008-07-01

    Within this thesis, several important subjects related to the use of amorphous silicon nitride made by plasma enhanced chemical vapour deposition as an anti-reflective coating on silicon solar cells are presented. The first part of the thesis covers optical simulations to optimise single and double layer anti-reflective coatings with respect to optical performance when situated on a silicon solar cell. The second part investigates the relationship between important physical properties of silicon nitride films when deposited under different conditions. The optical simulations were either based on minimising the reflectance off a silicon nitride/silicon wafer stack or maximising the transmittance through the silicon nitride into the silicon wafer. The former method allowed consideration of the reflectance off the back surface of the wafer, which occurs typically at wavelengths above 1000 nm due to the transparency of silicon at these wavelengths. However, this method does not take into consideration the absorption occurring in the silicon nitride, which is negligible at low refractive indexes but quite significant when the refractive index increases above 2.1. For high-index silicon nitride films, the latter method is more accurate as it considers both reflectance and absorbance in the film to calculate the transmittance into the Si wafer. Both methods reach similar values for film thickness and refractive index for optimised single layer anti-reflective coatings, due to the negligible absorption occurring in these films. For double layer coatings, though, the reflectance based simulations overestimated the optimum refractive index for the bottom layer, which would have lead to excessive absorption if applied to real anti-reflective coatings. The experimental study on physical properties for silicon nitride films deposited under varying conditions concentrated on the estimation of properties important for its applications, such as optical properties, passivation

  13. Nonisothermal desorption of droplets of complex compositions

    Directory of Open Access Journals (Sweden)

    Nakoryakov Vladimir E.

    2012-01-01

    Full Text Available This paper presents the process of nonstationary evaporation of aqueous solutions of LiBr-H2O, CaCl2-H2O, NaCl-H2O droplets on a horizontal heating surface. The following typical stages of heat and mass transfer depending on wall temperature have been considered: evaporation below boiling temperature and nucleate boiling. The significant decrease in desorption intensity with a rise of initial mass concentration of salt has been observed. Formation of a surface crystallization front at evaporation of a droplet has been detected. We have developed the experimental method for direct measurements of the mass of evaporating droplet.

  14. Nickel (II) ion desorption kinetic modeling from unmodified and ...

    African Journals Online (AJOL)

    The desorption of Ni2+ from three oil palm fruit fibre adsorbents (UOPF, 0.5MOPF and 1.0MOPF) using five desorbing solutions showed a desorption efficiency following the trend, 0.1M HCl > 0.1MH2SO4 > 0.1MHNO3 > 0.1MNaOH >hot deionized H2O. The Elovich desorption constant, β values for the 0.1MHCl desorbent ...

  15. Properties of NiO nanostructured growth using thermal dry oxidation of nickel metal thin film for hydrogen gas sensing at room temperature

    Science.gov (United States)

    Abubakar, Dauda; Ahmed, Naser M.; Mahmud, Shahrom; Algadri, Natheer A.

    2017-07-01

    A highly qualitative NiO nanostructure was synthesized using thermal dry oxidation of metallic Ni thin films on ITO/glass using the RF sputtering technique. The deposited nickel thin films were oxidized in air ambient at 550 °C inside a furnace. The structural and surface morphologies, and the electrical and gas sensing properties of the NiO nanostructure were examined. An x-ray diffraction analysis demonstrated that the NiO nanostructure has a cubic structure with orientation of the most intense peak at (2 0 0), and shows good crystalline quality. Finite-element scanning electron microscopy and energy dispersive x-ray spectroscopy results revealed O and Ni present in the treated samples, indicating a pure NiO nanostructure composition obtained with high porosity. The electrical properties of the oxidize Ni thin films showed a p-type NiO thin film semiconductor. A hydrogen gas sensing measurement was made at different operating temperatures and different gas concentrations with a detection limit of 30 ppm concentration. The sensor device shows great sensing properties with an excellent sensitivity (310%) at room temperature, which decreases with an increase in the operating temperature. Superfast response and recovery times of 6 and 0.5 s, respectively, were observed with the device at 150 °C operating temperature.

  16. Effects of sterilization with hydrogen peroxide gas plasma, ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints.

    Science.gov (United States)

    Gatineau, Matthieu; El-Warrak, Alexander O; Bolliger, Christian; Mourez, Michael; Berthiaume, Frederic

    2012-10-01

    To compare effects of sterilization with hydrogen peroxide gas plasma (HPGP), ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints. Samples of a 36.3-kg test nylon leader line, 57.8-kg test nylon fishing line, and 2-mm ultrahigh-molecular weight polyethylene (UHMWPE) were used. In this in vitro study, samples of nylon leader line, fishing line, and UHMWPE sterilized by use of HPGP, ethylene oxide, and steam or unsterilized samples were used. Bacterial adherence on unsterilized and sterilized samples was tested with Staphylococcus epidermidis and Escherichia coli. Five samples were examined for each line type and sterilization condition, and final colony counts were obtained. Bacterial adherence was significantly affected by method of sterilization for all 3 line types. For most of the samples, bacterial adherence was similar or lower when HPGP sterilization was used, compared with results for sterilization via ethylene oxide and steam, respectively. Bacterial adherence was significantly higher for UHMWPE, compared with adherence for the nylon line, regardless of the sterilization method used. Bacterial adherence was higher for nylon fishing line than for nylon leader line for S epidermidis after ethylene oxide sterilization and for E coli after HPGP and ethylene oxide sterilization. Effects of HPGP sterilization on bioadhesive properties of nylon and polyethylene lines compared favorably with those for ethylene oxide and steam sterilization. Also, nylon line may be a more suitable material than UHMWPE for suture prostheses on the basis of bacterial adherence properties.

  17. Hydrogen bonding and vibrational properties of hydroxy groups in the crystal lattice of dioctahedral clay minerals by means of first principles calculations

    Science.gov (United States)

    Botella, V.; Timon, V.; Escamilla-Roa, E.; Hernández-Languna, A.; Sainz-Díaz, C. I.

    2004-10-01

    The hydroxy groups of the crystal lattice of dioctahedral 2:1 phyllosilicates were investigated by means of quantum-mechanical calculation. The standard Kohn-Sham self-consistent density functional theory (DFT) method was applied using the generalized gradient approximation (GGA) with numerical atomic orbitals and double-zeta polarized functions as basis set. Isomorphous cation substitution of different cations in the octahedral and tetrahedral sheet was included along with several interlayer cations reproducing experimental crystal lattice parameters. The effect of these substitutions and the interlayer charge on the hydroxyl group properties was also studied. These structures represent different cation pairs among Al3+, Fe3+ and Mg2+ in the octahedral sheet of clays joined to OH groups. The geometrical disposition of the OH bond in the crystal lattice and the hydrogen bonds and other electrostatic interactions of this group were analyzed. The frequencies of different vibrational modes of the OH group [ν(OH), δ(OH) and γ(OH)] were calculated and compared with experimental data, finding a good agreement. These frequencies depend significantly on the nature of cations which are joined with, and the electrostatic interactions with, the interlayer cations. Besides, hydrogen-bonding interactions with tetrahedral oxygens are important for the vibrational properties of the OH groups; however, also the electrostatic interactions of these OH groups with the rest of tetrahedral oxygens within the tetrahedral cavity should be taken into account. The cation substitution effect on the vibration modes of the OH groups was analyzed reproducing the experimental behaviour.

  18. Substrate-Enhanced Micro Laser Desorption Ionization Mass Spectrometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne Research, Inc. and the University of Massachusetts at Amherst will collaborate to develop laser desorption ionization (LDI) mass spectrometric analysis of...

  19. Handheld hydrogen - a new concept for hydrogen storage

    DEFF Research Database (Denmark)

    Johannessen, Tue; Sørensen, Rasmus Zink

    2005-01-01

    A method of hydrogen storage using metal ammine complexes in combination with an ammonia decomposition catalyst is presented. This dense hydrogen storage material has high degree of safety compared to all the other available alternatives. This technology reduces the safety hazards of using liquid...... ammonia and benefits from the properties of ammonia as a fuel. The system can be used as a safe, reversible, low-cost hydrogen carrier....

  20. Study of Adsorption and Desorption Performances of Zr-Based Metal–Organic Frameworks Using Paper Spray Mass Spectrometry

    Science.gov (United States)

    Wang, Xiaoting; Chen, Ying; Zheng, Yajun

    2017-01-01

    The dynamic pore systems and high surface areas of flexible metal–organic framework materials make them excellent candidates to be used in different kinds of adsorption processes. However, the adsorption and desorption behaviors of therapeutic drugs on metal–organic frameworks in solution are not fully developed. Here, we systematically investigated the adsorption and desorption behaviors of a typical therapeutic drug, verapamil, over several Zr-based metal–organic frameworks [e.g., Zr-FUM, UiO-66(Zr), UiO-66(Zr)-NH2 and UiO-66(Zr)-2COOH] as well as ZrO2 in an acetonitrile solution by using paper spray mass spectrometry. In contrast to other materials, UiO-66(Zr)-2COOH demonstrated a superior adsorption performance to verapamil due to their strong acid-base and/or hydrogen-bond interactions, and the adsorption process fitted well with the pseudo-second-order kinetic model. As verapamil-adsorbed materials were used for desorption experiments, ZrO2 demonstrated the most favorable desorption performance, whereas UiO-66(Zr)-2COOH yielded the poorest desorption capability. These Zr-based materials had also been coated at the surface with filter papers for the analysis of various drugs and proteins in the process of paper spray mass spectrometry. The results demonstrated that among the studied materials, ZrO2-coated paper gave the most favorable desorption performance as a pure drug solution, whereas the paper from UiO-66(Zr) demonstrated the optimal capability in the analyses of therapeutic drugs in a complex matrix (e.g., blood) and a protein (e.g., myoglobin). PMID:28773131