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Sample records for borohydrides

  1. Method for producing a borohydride

    DOEpatents

    Kong, Peter C.

    2010-06-22

    A method for producing a borohydride is described that includes the steps of providing a source of borate; providing a material that chemically reduces the source of the borate to produce a borohydride; and reacting the source of the borate and the material by supplying heat at a temperature that substantially effects the production of the borohydride.

  2. Catalyzed borohydrides for hydrogen storage

    DOEpatents

    Au, Ming

    2012-02-28

    A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

  3. Hydrogen Generation Via Sodium Borohydride

    NASA Astrophysics Data System (ADS)

    Mohring, Richard M.; Wu, Ying

    2003-07-01

    Along with the technological challenges associated with developing fuel cells and hydrogen burning engines, a major issue that must be addressed to ensure the ultimate success of a hydrogen economy is the ability to store and transport hydrogen effectively. Millennium Cell has developed and patented a proprietary system for storing and generating hydrogen gas called Hydrogen on Demand™. The system releases the hydrogen stored in fuel solutions of sodium borohydride as needed through an easily controllable catalytic process. The fuel itself is water-based, rich in hydrogen content, and non-flammable. It can be stored in plastic containers under no pressure. After the hydrogen from the fuel is consumed, the remaining product, sodium metaborate (chemically similar to borax), can be recycled back into fresh fuel. In this paper, an overview of the Hydrogen on Demand™ technology is presented along with data showing the performance characteristics of practical hydrogen generation systems. A brief discussion of sodium borohydride regeneration chemistry is also provided.

  4. Direct synthesis of calcium borohydride

    DOEpatents

    Ronnebro, Ewa Carin Ellinor; Majzoub, Eric H.

    2009-10-27

    A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Ca(BH.sub.4).sub.2, from the alkaline earth metal hydride and the alkaline earth metal boride. The borohydride thus prepared is doped with a small portion of a metal chloride catalyst compound, such as RuCl.sub.3, TiCl.sub.3, or a mixture of TiCl.sub.3 and palladium metal. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen at about 70 MPa while heating the mixture to about 400.degree. C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.

  5. Chloride substitution in sodium borohydride

    SciTech Connect

    Ravnsbaek, Dorthe B.; Rude, Line H.; Jensen, Torben R.

    2011-07-15

    The dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH{sub 4}){sub 1-x}Cl{sub x} is studied. The dissolution reaction is facilitated by two methods: ball milling or combination of ball milling and annealing at 300 deg. C for three days of NaBH{sub 4}-NaCl samples in molar ratios of 0.5:0.5 and 0.75:0.25. The degree of dissolution is studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction (SR-PXD) data. The results show that dissolution of 10 mol% NaCl into NaBH{sub 4}, forming Na(BH{sub 4}){sub 0.9}Cl{sub 0.1}, takes place during ball milling. A higher degree of dissolution of NaCl in NaBH{sub 4} is obtained by annealing resulting in solid solutions containing up to 57 mol% NaCl, i.e. Na(BH{sub 4}){sub 0.43}Cl{sub 0.57}. In addition, annealing results in dissolution of 10-20 mol% NaBH{sub 4} into NaCl. The mechanism of the dissolution during annealing and the decomposition pathway of the solid solutions are studied by in situ SR-PXD. Furthermore, the stability upon hydrogen release and uptake were studied by Sieverts measurements. - Graphical Abstract: Dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH{sub 4}){sub 1-x}Cl{sub x} is studied. Dissolution is facilitated by two methods: ball milling or annealing at 300 deg. C for three days of NaBH{sub 4}-NaCl samples. Sample compositions and dissolution mechanism are studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction data. Highlights: > Studies of dissolution of sodium chloride and sodium borohydride into each other. > Solid state diffusion facilitated by mechanical and thermal treatments. > Dissolution is more efficiently induced by heating than by mechanical treatment. > Mechanism for dissolution studied by Rietveld refinement of in situ SR-PXD data.

  6. Direct synthesis of magnesium borohydride

    DOEpatents

    Ronnebro, Ewa Carin Ellinor; Severa, Godwin; Jensen, Craig M.

    2012-04-03

    A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Mg(BH.sub.4).sub.2, from the alkaline earth metal boride MgB.sub.2 by hydrogenating the MgB.sub.2 at an elevated temperature and pressure. The boride may also be doped with small amounts of a metal chloride catalyst such as TiCl.sub.3 and/or NiCl.sub.2. The process provides for charging MgB.sub.2 with high pressure hydrogen above at least 70 MPa while simultaneously heating the material to about 350.degree. C. to about 400.degree. C. The method is relatively simple and inexpensive and provides a reversible hydride compound having a hydrogen capacity of at least 11 wt %.

  7. Modified borohydrides for reversible hydrogen storage

    SciTech Connect

    Au, Ming

    2005-08-29

    In attempt to develop lithium borohydrides as the reversible hydrogen storage materials with the high capacity, the feasibility to reduce dehydrogenation temperature of the lithium borohydride and moderate rehydrogenation condition has been explored. The commercial available lithium borohydride has been modified by ball milling with metal oxides and metal chlorides as the additives. The modified lithium borohydrides release 9 wt% hydrogen starting from 473K. The dehydrided modified lithium borohydrides absorb 7-9 wt% hydrogen at 873K and 7 MPa. The additive modification reduces dehydriding temperature from 673K to 473K and moderates rehydrogenation conditions to 923K and 15 MPa. XRD and SEM analysis discovered the formation of the intermediate compound TiB{sub 2} that may plays the key role in change the reaction path resulting the lower dehydriding temperature and reversibility. The reversible hydrogen storage capacity of the oxide modified lithium borohydrides decreases gradually during hydriding-dehydriding cycling due to the lost of the boron during dehydrogenation. But, it can be prevented by selecting the suitable additive, forming intermediate boron compounds and changing the reaction path. The additives reduce dehydriding temperature and improve the reversibility, it also reduces the hydrogen storage capacity. The best compromise can be reached by optimization of the additive loading and introducing new process other than ball milling.

  8. Modified lithium borohydrides for reversible hydrogen storage.

    PubMed

    Au, Ming; Jurgensen, Arthur

    2006-04-01

    In an attempt to develop lithium borohydrides as reversible hydrogen storage materials with high hydrogen storage capacities, the feasibility of reducing the dehydrogenation temperature of the lithium borohydride and moderating rehydrogenation conditions was explored. The lithium borohydride was modified by ball milling with metal oxides and metal chlorides as additives. The modified lithium borohydrides released 9 wt % hydrogen starting from 473 K. The dehydrided modified lithium borohydrides absorbed 7-9 wt % hydrogen at 873 K and 7 MPa. The modification with additives reduced the dehydriding starting temperature from 673 to 473 K and moderated the rehydrogenation conditions from 923 K/15 MPa to 873 K/7 MPa. XRD and SEM analysis revealed the formation of an intermediate compound that might play a key role in changing the reaction path, resulting in the lower dehydriding temperature and reversibility. The reversible hydrogen storage capacity of the oxide-modified lithium borohydrides decreased gradually during hydriding/dehydriding cycling. One of the possible reasons for this effect might be the loss of boron during dehydrogenation, but this can be prevented by changing the dehydriding path using appropriate additives. The additives reduced the dehydriding temperature and improved the reversibility, but they also reduced the hydrogen storage capacity. The best compromise can be reached by selecting appropriate additives, optimizing the additive loading, and using new synthesis processes other than ball milling. PMID:16571023

  9. Static Compression of Tetramethylammonium Borohydride

    SciTech Connect

    Dalton, Douglas Allen; Somayazulu, M.; Goncharov, Alexander F.; Hemley, Russell J.

    2011-11-15

    Raman spectroscopy and synchrotron X-ray diffraction are used to examine the high-pressure behavior of tetramethylammonium borohydride (TMAB) to 40 GPa at room temperature. The measurements reveal weak pressure-induced structural transitions around 5 and 20 GPa. Rietveld analysis and Le Bail fits of the powder diffraction data based on known structures of tetramethylammonium salts indicate that the transitions are mediated by orientational ordering of the BH{sub 4}{sup -} tetrahedra followed by tilting of the (CH{sub 3}){sub 4}N{sup +} groups. X-ray diffraction patterns obtained during pressure release suggest reversibility with a degree of hysteresis. Changes in the Raman spectrum confirm that these transitions are not accompanied by bonding changes between the two ionic species. At ambient conditions, TMAB does not possess dihydrogen bonding, and Raman data confirms that this feature is not activated upon compression. The pressure-volume equation of state obtained from the diffraction data gives a bulk modulus [K{sub 0} = 5.9(6) GPa, K'{sub 0} = 9.6(4)] slightly lower than that observed for ammonia borane. Raman spectra obtained over the entire pressure range (spanning over 40% densification) indicate that the intramolecular vibrational modes are largely coupled.

  10. Detoxification of lignocellulosic hydrolysates using sodium borohydride.

    PubMed

    Cavka, Adnan; Jönsson, Leif J

    2013-05-01

    Addition of sodium borohydride to a lignocellulose hydrolysate of Norway spruce affected the fermentability when cellulosic ethanol was produced using Saccharomyces cerevisiae. Treatment of the hydrolysate with borohydride improved the ethanol yield on consumed sugar from 0.09 to 0.31 g/g, the balanced ethanol yield from 0.02 to 0.30 g/g, and the ethanol productivity from 0.05 to 0.57 g/(L×h). Treatment of a sugarcane bagasse hydrolysate gave similar results, and the experiments indicate that sodium borohydride is suitable for chemical in situ detoxification. The model inhibitors coniferyl aldehyde, p-benzoquinone, 2,6-dimethoxybenzoquinone, and furfural were efficiently reduced by treatment with sodium borohydride, even under mild reaction conditions (20 °C and pH 6.0). While addition of sodium dithionite to pretreatment liquid from spruce improved enzymatic hydrolysis of cellulose, addition of sodium borohydride did not. This result indicates that the strong hydrophilicity resulting from sulfonation of inhibitors by dithionite treatment was particularly important for alleviating enzyme inhibition. PMID:23567704

  11. Sodium Borohydride/Hydrogen Peroxide Fuel Cells For Space Application

    NASA Technical Reports Server (NTRS)

    Valdez, T. I.; Deelo, M. E.; Narayanan, S. R.

    2006-01-01

    This viewgraph presentation examines Sodium Borohydride and Hydrogen Peroxide Fuel Cells as they are applied to space applications. The topics include: 1) Motivation; 2) The Sodium Borohydride Fuel Cell; 3) Sodium Borohydride Fuel Cell Test Stands; 4) Fuel Cell Comparisons; 5) MEA Performance; 6) Anode Polarization; and 7) Electrode Analysis. The benefits of hydrogen peroxide as an oxidant and benefits of sodium borohydride as a fuel are also addressed.

  12. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  13. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  14. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  15. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  16. BIMETALLIC LITHIUM BOROHYDRIDES TOWARD REVERSIBLE HYDROGEN STORAGE

    SciTech Connect

    Au, M.

    2010-10-21

    Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic borohydrides, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species.

  17. Borohydrides: from sheet to framework topologies.

    PubMed

    Schouwink, P; Ley, M B; Jensen, T R; Smrčok, L'; Černý, R

    2014-06-01

    The five novel compounds ALiM(BH4)4 (A = K or Rb; M = Mg or Mn) and K3Li2Mg2(BH4)9 crystallizing in the space groups Aba2 and P2/c, respectively, represent the first two-dimensional topologies amongst homoleptic borohydrides. The crystal structures have been solved, refined and characterized by synchrotron X-ray powder diffraction, neutron powder diffraction and solid-state DFT calculations. Minimal energies of ordered models corroborate crystal symmetries retrieved from diffraction data. The layered Li-Mg substructure forms negatively charged uninodal 4-connected networks. It is shown that this connectivity cannot generate the long sought-after, bimetallic Li-Mg borohydrides without countercations when assuming preferred coordination polyhedra as found in Mg(BH4)2 and LiBH4. The general properties of the trimetallic compound series are analogous with the anhydrous aluminosilicates. Additionally, a relationship with zeolites is suggested, which are built from three-dimensional Al-Si-O networks with a negative charge on them. The ternary metal borohydride systems are of interest due to their potential as novel hydridic frameworks and will allow exploration of the structural chemistry of light-metal systems otherwise subject to eutectic melting. PMID:24699844

  18. Intrinsic borohydride fuel cell/battery hybrid power sources

    NASA Astrophysics Data System (ADS)

    Hong, Jian; Fang, Bin; Wang, Chunsheng; Currie, Kenneth

    The electrochemical oxidation behaviors of NaBH 4 on Zn, Zn-MH, and MH (metal-hydride) electrodes were investigated, and an intrinsic direct borohydride fuel cell (DBFC)/battery hybrid power source using MH (or Zn-MH) as the anode and MnO 2 as the cathode was tested. Borohydride cannot be effectively oxidized on Zn electrodes at the Zn oxidation potential because of the poor electrocatalytic ability of Zn for borohydride oxidation and the high overpotential, even though borohydride has the same oxidation potential of Zn in an alkaline solution. The borohydride can be electrochemically oxidized on Ni and MH electrodes through a 4e reaction at a high overpotential. Simply adding borohydride into an alkaline electrolyte of a Zn/air or MH/air battery can greatly increase the capacity, while an intrinsic DBFC/MH(or Zn)-MnO 2 battery can deliver a higher peak power than regular DBFCs.

  19. Quaternary ammonium borohydride adsorption in mesoporous silicate MCM-48

    SciTech Connect

    Wolverton, Michael J; Daemen, Luke L; Hartl, Monika A

    2010-01-01

    Inorganic borohydrides have a high gravimetric hydrogen density but release H2 only under energetically unfavorable conditions. Surface chemistry may help in lowering thermodynamic barriers, but inclusion of inorganic borohydrides in porous silica materials has proved hitherto difficult or impossible. We show that borohydrides with a large organic cation are readily adsorbed inside mesoporous silicates, particularly after surface treatment. Thermal analysis reveals that the decomposition thermodynamics of tetraalkylammonium borohydrides are substantially affected by inclusion in MCM-48. Inelastic neutron scattering (INS) data show that the compounds adsorb on the silica surface. Evidence of pore loading is supplemented by DSC/TGA, XRD, FTIR, and BET isotherm measurements. Mass spectrometry shows significant hydrogen release at lower temperature from adsorbed borohydrides in comparison with the bulk borohydrides. INS data measured for partially decomposed samples indicates that the decomposition of the cation and anion is likely simultaneous. Additionally, these data confirm the formation of Si-H bonds on the silica surface upon decomposition of adsorbed tetramethylammonium borohydride.

  20. Synthesis and Characterization of Methylammonium Borohydride

    SciTech Connect

    Graham, Kathryn R.; Bowden, Mark E.; Kemmitt, Tim

    2011-01-06

    A new borohydride, [CH3NH3]+[BH4]-, has been synthesised by the metathesis of CH3NH3X and MBH4 in methylamine in order to determine its behaviour in comparison to ammonium borohydride [NH4]+[BH4]-. The introduction of methyl groups is expected to disrupt the hydrogen bonding network of [NH4]+[BH4]- and in turn alter the hydrogen release properties. Room temperature X-ray diffraction studies have shown that [CH3NH3]+[BH4]- adopts a tetragonal unit cell with lattice parameters of a = 4.9486 Å and b = 8.9083 Å. The room temperature structure shows considerable hydrogen mobility similar to that observed in NH3BH3. The kinetics and thermodynamics of these reactions have been investigated and show hydrogen release follows a similar pathway to that of [NH4]+[BH4]-. Both compounds decompose slowly at room temperature and rapidly at ca. 40 °C to form the diammoniate of diborane or the methylated analogue [BH2(CH3NH2)2]+BH4-. The first stage of decomposition has been further investigated by means on in-situ X-ray diffraction and solid state 11B NMR spectroscopy, and appears to occur in the absence of any detectable intermediates to form crystalline [BH2(CH3NH2)2]+BH4-. [(CH3)2NH2]+[BH4]- and [BH2{(CH3)2NH}2]+BH4- have also been synthesised by analogous routes, indicating a more general applicability of the synthetic method.

  1. Catalytic polymeric electrodes for direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Bayatsarmadi, Bita; Peters, Alice; Talemi, Pejman

    2016-08-01

    The direct borohydride fuel cell (DBFC) is a new class of fuel cells that produces non-toxic by-products and has a potential for a high voltage and high energy density. A major challenge in developing efficient DBFCs is the development of an efficient, stable, and economic catalyst for the oxidation of borohydride. In this paper, we report the use of conducting polymer Poly(3,4-ethylenedioxythiophene) (PEDOT) as electrocatalysts in DBFC. PEDOT electrodes prepared by vacuum phase polymerization exhibited electrocatalytic behavior towards oxidation of borohydride and reduction of hydrogen peroxide. Spectroscopic analysis of samples showed that PEDOT can act as an interface for electron transfer from borohydride ions. Comparing the polarization curves of DBFCs with PEDOT coated on graphite electrodes and cells with bare graphite electrodes, demonstrated higher voltage, maximum power density, and stability.

  2. Method of recycling lithium borate to lithium borohydride through diborane

    DOEpatents

    Filby, Evan E.

    1976-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a diborane intermediate to complete the recycle scheme.

  3. Process for production of a borohydride compound

    DOEpatents

    Allen, Nathan Tait; Butterick, III, Robert; Chin, Arthur Achhing; Millar, Dean Michael; Molzahn, David Craig

    2014-08-19

    A process for production of a borohydride compound M(BH.sub.4).sub.y. The process has three steps. The first step combines a compound of formula (R.sup.1O).sub.yM with aluminum, hydrogen and a metallic catalyst containing at least one metal selected from the group consisting of titanium, zirconium, hafnium, niobium, vanadium, tantalum and iron to produce a compound of formula M(AlH.sub.3OR.sup.1).sub.y, wherein R.sup.1 is phenyl or phenyl substituted by at least one alkyl or alkoxy group; M is an alkali metal, Be or Mg; and y is one or two; wherein the catalyst is present at a level of at least 200 ppm based on weight of aluminum. The second step combines the compound of formula M(AlH.sub.3OR.sup.1).sub.y with a borate, boroxine or borazine compound to produce M(BH.sub.4).sub.y and a byproduct mixture containing alkali metal and aluminum aryloxides. The third step separates M(BH.sub.4).sub.y from the byproduct mixture.

  4. On the purity assessment of solid sodium borohydride

    NASA Astrophysics Data System (ADS)

    Botasini, Santiago; Méndez, Eduardo

    2012-01-01

    Since sodium borohydride has become extensively used as chemical hydrogen storage material in fuel cells, many techniques have been proposed to assess the purity of this substance. However, all of them are developed in aqueous media, where the reagent is unstable. In addition, its hygroscopic nature was difficults in any attempt to make precise quantifications. The present work compares three different methods, namely, voltammetric, titrimetric, and Fourier transformed infrared spectroscopy (FTIR) in order to assess the purity of sodium borohydride, using an expired and a new sodium borohydride samples as references. Our results show that only the FTIR measurements provide a simple and semi-quantitative means to assess the purity of sodium borohydride due to the fact that it is the only one that measures the sample in the solid state. A comparison between the experimental data and theoretical calculation reveals the identification of the absorption bands at 1437 cm-1 of sodium metaborate and 2291 cm-1 of sodium borohydride which represent a good fingerprint for the qualitative assessment of the sample quality.

  5. Methods to Stabilize and Destabilize Ammonium Borohydride

    SciTech Connect

    Nielsen, Thomas K.; Karkamkar, Abhijeet J.; Bowden, Mark E.; Besenbacher, Fleming; Jensen, Torben R.; Autrey, Thomas

    2013-01-21

    Ammonium borohydride, NH4BH4, has a high hydrogen content of ρm = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may be explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ΔT = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.

  6. Destabilized and catalyzed borohydride for reversible hydrogen storage

    DOEpatents

    Mohtadi, Rana F.; Zidan, Ragaiy; Gray, Joshua; Stowe, Ashley C.; Sivasubramanian, Premkumar

    2012-02-28

    A process of forming a hydrogen storage material, including the steps of: providing a borohydride material of the formula: M(BH.sub.4).sub.x where M is an alkali metal or an alkaline earth metal and 1.ltoreq.x.ltoreq.2; providing an alanate material of the formula: M.sub.1(AlH.sub.4).sub.x where M.sub.1 is an alkali metal or an alkaline earth metal and 1.ltoreq.x.ltoreq.2; providing a halide material of the formula: M.sub.2Hal.sub.x where M.sub.2 is an alkali metal, an alkaline earth metal or transition metal and Hal is a halide and 1.ltoreq.x.ltoreq.4; combining the borohydride, alanate and halide materials such that 5 to 50 molar percent from the borohydride material is present forming a reaction product material having a lower hydrogen release temperature than the alanate material.

  7. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl...

  8. Formation mechanisms and aggregation behavior of borohydride reduced silver particles

    SciTech Connect

    Hyning, D.L. van; Zukoski, C.F.

    1998-11-24

    In this work, the authors examine the formation mechanisms of nanoscale silver particles produced by the reduction of silver perchlorate with sodium borohydride. Evidence is presented that the reaction pathway does not follow classical nucleation and growth theory, but is dominated by colloidal interactions. Upon injection of silver into a sodium borohydride solution, a molecular species absorbing at 220 nm is produced in less than 1 s. The authors suggest that this species contains borohydride nd small particles of reduced silver. The reaction mixture is initially dark as the result of the aggregation of the small silver particles into larger particles which have broad absorption spectra. During an intermediate stage, transmission electron microscopy and absorbance data show that even larger ({approximately}6--10 nm) particles grow at the expense of the monomeric silver particles. Later in the reaction, electrochemical potential measurements show that the borohydride concentration suddenly decreases. Direct measurement of interparticle forces demonstrate that this change in the solution conditions drives the particle surface potential toward zero and results in increased adhesive forces. The resulting aggregation manifests itself in a darkening of the solution temperatures, the increase is minimal. This effect can be linked to the number of monomeric silver particles remaining during the final transition.

  9. Barium borohydride chlorides: synthesis, crystal structures and thermal properties.

    PubMed

    Grube, Elisabeth; Olesen, Cathrine H; Ravnsbæk, Dorthe B; Jensen, Torben R

    2016-05-10

    Here we report the synthesis, mechanism of formation, characterization and thermal decomposition of new barium borohydride chlorides prepared by mechanochemistry and thermal treatment of MBH4-BaCl2, M = Li, Na or K in ratios 1 : 1 and 1 : 2. Initially, orthorhombic barium chloride, o-BaCl2 transforms into o-Ba(BH4)xCl2-x, x ∼ 0.15. Excess LiBH4 leads to continued anion substitution and a phase transformation into hexagonal barium borohydride chloride h-Ba(BH4)xCl2-x, which accommodates higher amounts of borohydride, possibly x ∼ 0.85 and resembles h-BaCl2. Thus, two solid solutions are in equilibrium during mechano-chemical treatment of LiBH4-BaCl2 (1 : 1) whereas LiBH4-BaCl2 (2 : 1) converts to h-Ba(BH4)0.85Cl1.15. Upon thermal treatment at T > ∼200 °C, h-Ba(BH4)0.85Cl1.15 transforms into another orthorhombic barium borohydride chloride compound, o-Ba(BH4)0.85Cl1.15, which is structurally similar to o-BaBr2. The samples with M = Na and K have lower reactivity and form o-Ba(BH4)xCl2-x, x ∼ 0.1 and a solid solution of sodium chloride dissolved in solid sodium borohydride, Na(BH4)1-xClx, x = 0.07. The new compounds and reaction mechanisms are investigated by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mass spectroscopy (MS) and temperature programmed photographic analysis (TPPA). PMID:27109871

  10. Novel Convenient Synthesis of (10)B-Enriched Sodium Borohydride.

    PubMed

    Safronov, Alexander V; Jalisatgi, Satish S; Hawthorne, M Frederick

    2016-06-01

    A convenient and efficient synthesis of (10)B-enriched sodium borohydride [Na(10)BH4] from commercially available (10)B-enriched boric acid [(10)B(OH)3] is described. The reaction sequence (10)B(OH)3 → (10)B(On-Bu)3 → (10)BH3·Et3N → Na(10)BH4 afforded the product in 60-80% yield. The reaction was successfully scaled to hundreds of gram per run. PMID:27195803

  11. Method of generating hydrogen gas from sodium borohydride

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2007-12-11

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  12. Method of Manufacturing Micro-Disperse Particles of Sodium Borohydride

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester. Alan P.; Bell, Nelson S.

    2008-09-23

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  13. Ammine Calcium and Strontium Borohydrides: Syntheses, Structures, and Properties.

    PubMed

    Jepsen, Lars H; Lee, Young-Su; Černý, Radovan; Sarusie, Ram S; Cho, Young Whan; Besenbacher, Flemming; Jensen, Torben R

    2015-10-26

    A new series of solvent- and halide-free ammine strontium metal borohydrides Sr(NH3 )n (BH4 )2 (n=1, 2, and 4) and further investigations of Ca(NH3 )n (BH4 )2 (n=1, 2, 4, and 6) are presented. Crystal structures have been determined by powder XRD and optimized by DFT calculations to evaluate the strength of the dihydrogen bonds. Sr(NH3 )(BH4 )2 (Pbcn) and Sr(NH3 )2 (BH4 )2 (Pnc2) are layered structures, whereas M(NH3 )4 (BH4 )2 (M=Ca and Sr; P21 /c) are molecular structures connected by dihydrogen bonds. Both series of compounds release NH3 gas upon thermal treatment if the partial pressure of ammonia is low. Therefore, the strength of the dihydrogen bonds, the structure of the compounds, and the NH3 /BH4 (-) ratio for M(NH3 )n (BH4 )m have little influence on the composition of the released gasses. The composition of the released gas depends mainly on the thermal stability of the ammine metal borohydride and the corresponding metal borohydride. PMID:26364708

  14. A composite of borohydride and super absorbent polymer for hydrogen generation

    NASA Astrophysics Data System (ADS)

    Li, Z. P.; Liu, B. H.; Liu, F. F.; Xu, D.

    To develop a hydrogen source for underwater applications, a composite of sodium borohydride and super absorbent polymer (SAP) is prepared by ball milling sodium borohydride powder with SAP powder, and by dehydrating an alkaline borohydride gel. When sodium polyacrylate (NaPAA) is used as the SAP, the resulting composite exhibits a high rate of borohydride hydrolysis for hydrogen generation. A mechanism of hydrogen evolution from the NaBH 4-NaPAA composite is suggested based on structure analysis by X-ray diffraction and scanning electron microscopy. The effects of water and NiCl 2 content in the precursor solution on the hydrogen evolution behavior are investigated and discussed.

  15. Borohydride Ionic Liquids as Hypergolic Fuels: A Quest for Improved Stability.

    PubMed

    Chand, Deepak; Zhang, Jiaheng; Shreeve, Jean'ne M

    2015-09-14

    Hydrazine and its derivatives are used as fuels in rocket propellant systems; however, due to high vapor pressure, toxicity, and carcinogenicity, handling of such compounds is extremely hazardous. Hypergolic ionic liquids have shown great promise to become viable replacements for hydrazines as fuels. Borohydride-containing ionic liquids have now been synthesized using a more efficient synthetic pathway that does not require liquid ammonia and halide precursors. Among the eight new compounds, 1-allyl-3-n-butyl-imidazolium borohydride (1) and 1, 3-diallylimidazolium borohydride (5) exhibit very short ignition-delay times (ID) of 8 and 3 ms, respectively. The hydrolytic stability of borohydride compounds has been greatly improved by attaching long-chain alkyl substituents to the imidazole ring. 1,3-Di-(n-octyl)-imidazolium borohydride (3) is a water stable borohydride-containing ionic liquid. 1,3-Di-(n-butyl)-imidazolium borohydride (2) is a unique example of a borohydride liquid crystal. These ionic liquids have some unusual advantages, including negligible vapor pressures, good ignition delay (ID) times, and reduced synthetic and storage costs, thereby showing good application potential as environmentally friendly fuels in bipropellant formulations. In addition, they also have potential applications in the form of reducing agents and hydrogen storage materials. PMID:26223830

  16. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    NASA Astrophysics Data System (ADS)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  17. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    NASA Astrophysics Data System (ADS)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-06-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  18. Magnesium Borohydride as a Hydrogen Storage Material: Synthesis of Unsolvated Mg(BH4)2

    SciTech Connect

    Soloveichik, G.; Andrus, M; Gao, Y; Zhao, J; Kniajanski, S

    2009-01-01

    Different methods for preparation of unsolvated magnesium borohydride, a promising material for hydrogen storage, based on exchange reaction of MgCl2 with lithium and sodium borohydride in different solvents have been evaluated. A convenient scalable method for synthesis of pure Mg(BH4)2 by ball milling a mixture of MgCl2 and NaBH4 in diethyl ether has been developed. Crystalline stable low and high temperature phases, as well as a new metastable phase of unsolvated magnesium borohydride have been prepared.

  19. Complex metal borohydrides: multifunctional materials for energy storage and conversion.

    PubMed

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world's energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future. PMID:27384871

  20. Complex metal borohydrides: multifunctional materials for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world’s energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future.

  1. Modified lithium borohydrides for reversible hydrogen storage (2).

    PubMed

    Au, Ming; Jurgensen, Arthur; Zeigler, Kristine

    2006-12-28

    This paper reports the results of the effort to destabilize lithium borohydride for reversible hydrogen storage. Various metals, metal hydrides, and metal chlorides were selected and evaluated as destabilization agents for reducing dehydriding temperatures and improving dehydriding/rehydriding reversibility. The most effective material was LiBH4 + 0.2MgCl2 + 0.1TiCl3 which starts desorbing 5 wt % of hydrogen at 60 degrees C and can be rehydrogenated to 4.5 wt % at 600 degrees C and 70 bar. X-ray diffraction and Raman spectroscopic analysis show the interaction of LiBH4 with additives and the unusual change of B-H stretching. PMID:17181309

  2. Sodium borohydride/chloranil-based assay for quantifying total flavonoids.

    PubMed

    He, Xiangjiu; Liu, Dong; Liu, Rui Hai

    2008-10-22

    A novel sodium borohydride/chloranil-based (SBC) assay for quantifying total flavonoids, including flavones, flavonols, flavonones, flavononols, isoflavonoids, flavanols, and anthocyanins, has been developed. Flavonoids with a 4-carbonyl group were reduced to flavanols using sodium borohydride catalyzed with aluminum chloride. Then the flavan-4-ols were oxidized to anthocyanins by chloranil in an acetic acid solution. The anthocyanins were reacted with vanillin in concentrated hydrochloric acid and then quantified spectrophotometrically at 490 nm. A representative of each common flavonoid class including flavones (baicalein), flavonols (quercetin), flavonones (hesperetin), flavononols (silibinin), isoflavonoids (biochanin A), and flavanols (catechin) showed excellent linear dose-responses in the general range of 0.1-10.0 mM. For most flavonoids, the detection limit was about 0.1 mM in this assay. The recoveries of quercetin from spiked samples of apples and red peppers were 96.5 +/- 1.4% (CV = 1.4%, n = 4) and 99.0 +/- 4.2% (CV = 4.2%, n = 4), respectively. The recovery of catechin from spiked samples of cranberry extracts was 97.9 +/- 2.0% (CV = 2.0%, n = 4). The total flavonoids of selected common fruits and vegetables were measured using this assay. Among the samples tested, blueberry had the highest total flavonoid content (689.5 +/- 10.7 mg of catechin equiv per 100 g of sample), followed by cranberry, apple, broccoli, and red pepper. This novel SBC total flavonoid assay can be widely used to measure the total flavonoid content of fruits, vegetables, whole grains, herbal products, dietary supplements, and nutraceutical products. PMID:18798633

  3. Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved reversible hydrogen storage.

    PubMed

    Comănescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

    2012-09-28

    Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH(4))(2) was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and performance of hydrogen storage compared to unsupported borohydride. Hydrogen release from the supported hydride started at a temperature as low as 100 °C and the dehydrogenation rate was fast compared to the bulk borohydride. In addition, the hydrogen pressure necessary to regenerate the borohydride from the dehydrogenation products was reduced. PMID:22948563

  4. Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation

    NASA Astrophysics Data System (ADS)

    Sison Escaño, Mary Clare; Lacdao Arevalo, Ryan; Gyenge, Elod; Kasai, Hideaki

    2014-09-01

    The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4- on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

  5. Three-dimensional nanostructured Ni-Cu foams for borohydride oxidation

    NASA Astrophysics Data System (ADS)

    Santos, D. M. F.; Eugénio, S.; Cardoso, D. S. P.; Šljukić, B.; Montemor, M. F.

    2015-12-01

    Three-dimensional (3D) nanostructured nickel-copper (Ni-Cu) foams have been prepared by electrodeposition using a dynamic hydrogen template. These 3D materials were tested as electrodes for the borohydride oxidation reaction (BOR) in alkaline media for possible application as anodes of direct borohydride fuel cells. Their activity in BOR was studied using cyclic voltammetry, chronoamperometry, and chronopotentiometry and main reaction parameters and electrodes' stability were evaluated.

  6. A theoretical study of the structure and stability of borohydride on 3d transition metals

    NASA Astrophysics Data System (ADS)

    Arevalo, Ryan Lacdao; Escaño, Mary Clare Sison; Gyenge, Elod; Kasai, Hideaki

    2012-12-01

    The adsorption of borohydride on 3d transition metals (Cr, Mn, Fe, Co, Ni and Cu) was studied using first principles calculations within spin-polarized density functional theory. Magnetic effect on the stability of borohydride is noted. Molecular adsorption is favorable on Co, Ni and Cu, which is characterized by the strong s-dzz hybridization of the adsorbate-substrate states. Dissociated adsorption structure yielding one or two H adatom fragments on the surface is observed for Cr, Mn and Fe.

  7. Method of recycling lithium borate to lithium borohydride through methyl borate

    DOEpatents

    Filby, Evan E.

    1977-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a methyl borate intermediate to complete the recycle scheme.

  8. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    PubMed

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials. PMID:26634719

  9. Sodium borohydride removes aldehyde inhibitors for enhancing biohydrogen fermentation.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Zhou, Junhu; Cen, Kefa

    2015-12-01

    To enhance biohydrogen production from glucose and xylose in the presence of aldehyde inhibitors, reducing agent (i.e., sodium borohydride) was in situ added for effective detoxification. The detoxification efficiencies of furfural (96.7%) and 5-hydroxymethylfurfural (5-HMF, 91.7%) with 30mM NaBH4 were much higher than those of vanillin (77.3%) and syringaldehyde (69.3%). Biohydrogen fermentation was completely inhibited without detoxification, probably because of the consumption of nicotinamide adenine dinucleotide (NADH) by inhibitors reduction (R-CHO+2NADH→R-CH2OH+2NAD(+)). Addition of 30mM NaBH4 provided the reducing power necessary for inhibitors reduction (4R-CHO+NaBH4+2H2O→4R-CH2OH+NaBO2). The recovered reducing power in fermentation resulted in 99.3% recovery of the hydrogen yield and 64.6% recovery of peak production rate. Metabolite production and carbon conversion after detoxification significantly increased to 63.7mM and 81.9%, respectively. PMID:26342346

  10. Promoted dehydrogenation in ammine lithium borohydride supported by carbon nanotubes.

    PubMed

    Chen, Xinyi; Li, Shaofeng; Guo, Yanhui; Yu, Xuebin

    2011-10-14

    In this paper, ammine lithium borohydride (LiBH(4)·NH(3)) was successfully impregnated into multi-walled carbon nanotubes (CNTs) through a melting technique. X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller, and density measurements were employed to confirm the formation of the nanostructured LiBH(4)·NH(3)/CNTs composites. As a consequence, it was found that the dehydrogenation of the loaded LiBH(4)·NH(3) was remarkably enhanced, showing an onset dehydrogenation at temperatures below 100 °C, together with a prominent desorption of pure hydrogen at around 280 °C, with a capacity as high as 6.7 wt.%, while only a trace of H(2) liberation was present for the pristine LiBH(4)·NH(3) in the same temperature range. Structural examination indicated that the significant modification of the thermal decomposition route of LiBH(4)·NH(3) achieved in the present study is due to the CNT-assisted formation of B-N-based hydride composite, starting at a temperature below 100 °C. It is demonstrated that the formation of this B-N-based hydride covalently stabilized the [NH] groups that were weakly coordinated on Li cations in the pristine LiBH(4)·NH(3)via strong B-N bonds, and furthermore, accounted for the substantial hydrogen desorption at higher temperatures. PMID:21850349

  11. Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

    PubMed

    Budroni, M A; Biosa, E; Garroni, S; Mulas, G R C; Marchettini, N; Culeddu, N; Rustici, M

    2013-11-14

    The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel. PMID:24084866

  12. Synthesis and thermal decomposition behaviors of magnesium borohydride ammoniates with controllable composition as hydrogen storage materials.

    PubMed

    Yang, Yanjing; Liu, Yongfeng; Li, You; Gao, Mingxia; Pan, Hongge

    2013-02-01

    An ammonia-redistribution strategy for synthesizing metal borohydride ammoniates with controllable coordination number of NH(3) was proposed, and a series of magnesium borohydride ammoniates were easily synthesized by a mechanochemical reaction between Mg(BH(4))(2) and its hexaammoniate. A strong dependence of the dehydrogenation temperature and purity of the released hydrogen upon heating on the coordination number of NH(3) was elaborated for Mg(BH(4))(2)·xNH(3) owing to the change in the molar ratio of H(δ+) and H(δ-), the charge distribution on H(δ+) and H(δ-), and the strength of the coordinate bond N:→Mg(2+). The monoammoniate of magnesium borohydride (Mg(BH(4))(2)·NH(3)) was obtained for the first time. It can release 6.5% pure hydrogen within 50 minutes at 180 °C. PMID:23192895

  13. A comparison of sodium borohydride as a fuel for proton exchange membrane fuel cells and for direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Wee, Jung-Ho

    Two types of fuel cell systems using NaBH 4 aqueous solution as a fuel are possible: the hydrogen/air proton exchange membrane fuel cell (PEMFC) which uses onsite H 2 generated via the NaBH 4 hydrolysis reaction (B-PEMFC) at the anode and the direct borohydride fuel cell (DBFC) system which directly uses NaBH 4 aqueous solution at the anode and air at the cathode. Recently, research on these two types of fuel cells has begun to attract interest due to the various benefits of this liquid fuel for fuel cell systems for portable applications. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two fuel cells. Considering their current technologies and the high price of NaBH 4, this paper evaluated and analyzed the factors influencing the relative favorability of each type of fuel cell. Their relative competitiveness was strongly dependent on the extent of the NaBH 4 crossover. When considering the crossover in DBFC systems, the total costs of the B-PEMFC system were the most competitive among the fuel cell systems. On the other hand, if the crossover problem were to be completely overcome, the total cost of the DBFC system generating six electrons (6e-DBFC) would be very similar to that of the B-PEMFC system. The DBFC system generating eight electrons (8e-DBFC) became even more competitive if the problem of crossover can be overcome. However, in this case, the volume of NaBH 4 aqueous solution consumed by the DBFC was larger than that consumed by the B-PEMFC.

  14. A Guided-Inquiry Approach to the Sodium Borohydride Reduction and Grignard Reaction of Carbonyl Compounds

    ERIC Educational Resources Information Center

    Rosenberg, Robert E.

    2007-01-01

    The guided-inquiry approach is applied to the reactions of sodium borohydride and phenyl magnesium bromide with benzaldehyde, benzophenone, benzoic anhydride, and ethyl benzoate. Each team of four students receives four unknowns. Students identify the unknowns and their reaction products by using the physical state of the unknown, an…

  15. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

    PubMed Central

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-01-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

  16. By-Product Carrying Humidified Hydrogen: An Underestimated Issue in the Hydrolysis of Sodium Borohydride.

    PubMed

    Petit, Eddy; Miele, Philippe; Demirci, Umit B

    2016-07-21

    Catalyzed hydrolysis of sodium borohydride generates up to four molecules of hydrogen, but contrary to what has been reported so far, the humidified evolved gas is not pure hydrogen. Elemental and spectroscopic analyses show, for the first time, that borate by-products pollute the stream as well as the vessel. PMID:27333077

  17. Tailoring the properties of ammine metal borohydrides for solid-state hydrogen storage.

    PubMed

    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), while metal borohydrides with high electronegativity (χp >∼1.6) are generally stabilized. PMID:25821161

  18. Borohydride Reduction of Estrone: Demonstration of Diastereoselectivity in the Undergraduate Organic Chemistry Laboratory

    ERIC Educational Resources Information Center

    Aditya, Animesh; Nichols, David E.; Loudon, G. Marc

    2008-01-01

    This experiment presents a guided-inquiry approach to the demonstration of diastereoselectivity in an undergraduate organic chemistry laboratory. Chiral hindered ketones such as estrone, undergo facile reduction with sodium borohydride in a highly diastereoselective manner. The diastereomeric estradiols produced in the reaction can be analyzed and…

  19. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage.

    PubMed

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-01-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a 'pen' for writing, which is accomplished by exfoliating GNs with the 'printed' borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

  20. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-08-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications.

  1. A Microwave-Assisted Reduction of Cyclohexanone Using Solid-State-Supported Sodium Borohydride

    ERIC Educational Resources Information Center

    White, Lori L.; Kittredge, Kevin W.

    2005-01-01

    The reduction of carbonyl groups by sodium borohydride though is a well-known reaction in most organic lab texts, a difficulty for an instructor adopting this reaction in a student lab is that it is too long. Using a microwave assisted organic synthesis solves this difficulty and one such reaction, which is the microwave-assisted reduction of…

  2. Exploiting hydrophobic borohydride-rich ionic liquids as faster-igniting rocket fuels.

    PubMed

    Liu, Tianlin; Qi, Xiujuan; Huang, Shi; Jiang, Linhai; Li, Jianling; Tang, Chenglong; Zhang, Qinghua

    2016-02-01

    A family of hydrophobic borohydride-rich ionic liquids was developed, which exhibited the shortest ignition delay times of 1.7 milliseconds and the lowest viscosity (10 mPa s) of hypergolic ionic fluids, demonstrating their great potential as faster-igniting rocket fuels to replace toxic hydrazine derivatives in liquid bipropellant formulations. PMID:26687630

  3. Further studies on vinamidinium salt amine exchange reactions, borohydride reductions and subsequent transformations

    PubMed Central

    Gupton, John T.; Telang, Nakul; Jia, Xin; Giglio, Benjamin C.; Eaton, James E.; Barelli, Peter J.; Hovaizi, Mona; Hall, Kayleigh E.; Welden, R. Scott; Keough, Matthew J.; Worrall, Eric F.; Finzel, Kara L.; Kluball, Emily J.; Kanters, Rene P.F.; Smith, Timothy M.; Smith, Stanton Q.; Nunes, Shane R.; Wright, Mathew T.; Birnstihl, Jennifer M.

    2010-01-01

    Studies directed at the amine exchange reaction of vinamidinium salts followed by sodium borohydride reduction to secondary and tertiary allylic amines are described. The tertiary allylic amines were alkylated and subjected to base mediated rearrangement to yield a variety of highly functionalized tertiary homoallylic amines. PMID:21113324

  4. Electrochemical research in chemical hydrogen storage materials: Sodium borohydride and organotin hydrides

    NASA Astrophysics Data System (ADS)

    McLafferty, Jason

    Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from "spent fuel," i.e., the material remaining after discharge of hydrogen. In this thesis, some research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the previous literature for electrochemical reduction of spent fuels, have been attempted. A quantitative analytical method for measuring the concentration of sodium borohydride in alkaline aqueous solution has been developed as part of this work and is described herein. Finally, findings from stability tests for sodium borohydride in aqueous solutions of several different compositions are reported. For aminoborane, other research institutes have developed regeneration schemes involving tributyltin hydride. In this thesis, electrochemical reduction experiments attempting to regenerate tributyltin hydride from tributyltin chloride (a representative by-product of the regeneration scheme) are described. These experiments were performed in the non-aqueous solvents acetonitrile and 1,2-dimethoxyethane. A non-aqueous reference electrode for electrolysis experiments in acetonitrile was developed and is described.

  5. Probing the pH dependent optical properties of aquatic, terrestrial and microbial humic substances by sodium borohydride reduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemically reducing humic (HA) and fulvic acids (FA) provides insight into spectroscopically identifiable structural moieties generating the optical properties of HA/FA from aquatic, microbial and terrestrial sources. Sodium borohydride reduction provides targeted reduction of carbonyl groups. The...

  6. Efficient hydrogen generation from sodium borohydride hydrolysis using silica sulfuric acid catalyst

    NASA Astrophysics Data System (ADS)

    Manna, Joydev; Roy, Binayak; Sharma, Pratibha

    2015-02-01

    A heterogeneous acid catalyst, silica sulfuric acid, was prepared from silica gel (SiO2) and sulfuric acid (H2SO4). Addition of SO3H functional group to SiO2 has been confirmed through various characterization techniques. The effect of this heterogeneous acid catalyst on hydrogen generation from sodium borohydride hydrolysis reaction was studied for different ratios of catalyst to NaBH4 and at different temperatures. The catalyst exhibited high catalytic activity towards sodium borohydride hydrolysis reaction. The activation energy of the NaBH4 hydrolysis reaction in the presence of silica sulfuric acid was calculated to be the lowest (17 kJ mol-1) among reported heterogeneous catalysts till date.

  7. Studies on sodium-borohydride-reducible hexose in glucosyl-albumin.

    PubMed

    Sharma, K K; Rai, K B; Pattabiraman, T N

    1983-08-01

    Glucosylated albumin of human serum isolated by dye-ligand chromatography on blue Sepharose, was not found to be completely reducible by sodium borohydride. The percentage reducible hexose as judged by phenol-sulphuric acid reaction was in the range of 49.7 +/- 12.8 in control subjects (n = 24) and 53.8 +/- 14.2 in diabetics (n = 50). Increase in the level of total hexose bound to albumin and reducible hexose were equally significant in diabetes (P less than 0.001). Sodium chloride gradient elution during chromatography on blue Sepharose showed that glucosylated albumin had lesser affinity than the native protein to the matrix. It is proposed that an addition product between hexose and albumin is formed during nonenzymatic reaction and this adduct is fairly stable and is not reducible by sodium borohydride. PMID:6626188

  8. Reversible Dehydrogenation of Magnesium Borohydride to Magnesium Triborane in the Solid State Under Moderate Conditions

    SciTech Connect

    Chong, Marina; Karkamkar, Abhijeet J.; Autrey, Thomas; Orimo, Shin-ichi; Jalisatgi, Satish; Jensen, Craig M.

    2011-02-17

    Thermal decomposition of magnesium borohydride, Mg(BH4)2, in the solid state was studied by a combination of PCT, TGA/MS and NMR spectroscopy. Dehydrogenation of Mg(BH4)2 at 200 °C, results in the highly selective formation of magnesium triborane, Mg(B3H8)2. This process is reversible at 250 °C under 120 atm H2. Dehydrogenation at higher temperature, > 300 °C, produces a complex mixture of polyborane species. Solution phase 11B NMR spectra of the hydrolyzed decomposition products reveals the formation of the B3H8 anion, boric acid from hydrolysis of the unstable polyboranes (BnHx) (n = 3-11, x >8), and the closoborane B12H12 dianion as a minor product. A BH condensation mechanism involving metal hydride formation is proposed to explain the limited reversible hydrogen storage in magnesium borohydride.

  9. Platinum-rare earth cathodes for direct borohydride-peroxide fuel cells

    NASA Astrophysics Data System (ADS)

    Cardoso, D. S. P.; Santos, D. M. F.; Šljukić, B.; Sequeira, C. A. C.; Macciò, D.; Saccone, A.

    2016-03-01

    Hydrogen peroxide (H2O2) is being actively investigated as an oxidant for direct borohydride fuel cells. Herein, platinum-rare earth (RE = Sm, Dy, Ho) alloys are prepared by arc melting and their activity for hydrogen peroxide reduction reaction (HPRR) is studied in alkaline media. Cyclic voltammetry and chronoamperometry measurements show that Pt-Sm electrode displays the highest catalytic activity for HPRR with the lowest activation energy, followed by Pt-Ho, while Pt-Dy alloys show practically no activity. Laboratory direct borohydride-peroxide fuel cells (DBPFCs) are assembled using these alloys. The DBPFC with Pt-Sm cathode gives the highest peak power density of 85 mW cm-2, which is more than double of that obtained in a DBPFC with Pt electrodes.

  10. Structure and spectroscopy of CuH prepared via borohydride reduction

    PubMed Central

    Bennett, Elliot L.; Wilson, Thomas; Murphy, Patrick J.; Refson, Keith; Hannon, Alex C.; Imberti, Silvia; Callear, Samantha K.; Chass, Gregory A.; Parker, Stewart F.

    2015-01-01

    Copper(I) hydride (cuprous hydride, CuH) was the first binary metal hydride to be discovered (in 1844) and is singular in that it is synthesized in solution, at ambient temperature. There are several synthetic paths to CuH, one of which involves reduction of an aqueous solution of CuSO4·5H2O by borohydride ions. The product from this procedure has not been extensively characterized. Using a combination of diffraction methods (X-ray and neutron) and inelastic neutron scattering spectroscopy, we show that the CuH from the borohydride route has the same bulk structure as CuH produced by other routes. Our work shows that the product consists of a core of CuH with a shell of water and that this may be largely replaced by ethanol. This offers the possibility of modifying the properties of CuH produced by aqueous routes. PMID:26634717

  11. Direct Hydrogenation Magnesium Boride to Magnesium Borohydride: Demonstration of >11 Weight Percent Reversible Hydrogen Storage

    SciTech Connect

    Severa, Godwin; Ronnebro, Ewa; Jensen, Craig M.

    2010-11-16

    We here for the first time demonstrate direct hydrogenation of magnesium boride, MgB2, to magnesium borohydride, Mg(BH4)2 at 900 bar H2-pressures and 400°C. Upon 14.8wt% hydrogen release, the end-decomposition product of Mg(BH4)2 is MgB2, thus, this is a unique reversible path here obtaining >11wt% H2 which implies promise for a fully reversible hydrogen storage material.

  12. Catalytic hydrodechlorination of 1,2-dichloroethane using copper nanoparticles under reduction conditions of sodium borohydride.

    PubMed

    Huang, Chang-Chieh; Lo, Shang-Lien; Tsai, Shin-Mu; Lien, Hsing-Lung

    2011-09-01

    1,2-Dichloroethane (1,2-DCA) is a raw material used for the manufacture of vinyl chloride monomer (VCM) and therefore has very often been detected in the groundwater nearby the VCM manufacturing plant. Zero-valent iron (ZVI) is capable of degrading a wide array of highly chlorinated contaminants; however, the reactivity of ZVI towards 1,2-DCA is very low. In this study, zero-valent copper nanoparticles have been synthesized for effective dechlorination of 1,2-DCA under reduction conditions of sodium borohydride. Copper nanoparticles consisted of mainly metallic copper (Cu(0)) with small amounts of cuprous oxide (Cu(2)O). They have surface areas of about 19.0 m(2) g(-1) and an average diameter of 15 nm. Batch experiments were conducted to test the effectiveness of copper nanoparticles for 1,2-DCA degradation using sodium borohydride as electron donors where the ORP was measured as -1100 mV. More than 80% of 1,2-DCA (30 mg L(-1)) was rapidly degraded within 2 h in the presence of both copper nanoparticles (2.5 g L(-1)) and borohydride (25 mM). No reduction of 1,2-DCA was observed when the system contained either copper nanoparticles alone or borohydride alone. The degradation intermediates included ethane and ethylene accounting for 79% and ∼1.5% of the 1,2-DCA lost, respectively. Potential environmental applications can be achieved by immobilizing copper nanoparticles onto the surface of reducing metals to form a reactive bimetallic structure. PMID:21850296

  13. Evaluation of anode (electro)catalytic materials for the direct borohydride fuel cell: Methods and benchmarks

    NASA Astrophysics Data System (ADS)

    Olu, Pierre-Yves; Job, Nathalie; Chatenet, Marian

    2016-09-01

    In this paper, different methods are discussed for the evaluation of the potential of a given catalyst, in view of an application as a direct borohydride fuel cell DBFC anode material. Characterizations results in DBFC configuration are notably analyzed at the light of important experimental variables which influence the performances of the DBFC. However, in many practical DBFC-oriented studies, these various experimental variables prevent one to isolate the influence of the anode catalyst on the cell performances. Thus, the electrochemical three-electrode cell is a widely-employed and useful tool to isolate the DBFC anode catalyst and to investigate its electrocatalytic activity towards the borohydride oxidation reaction (BOR) in the absence of other limitations. This article reviews selected results for different types of catalysts in electrochemical cell containing a sodium borohydride alkaline electrolyte. In particular, propositions of common experimental conditions and benchmarks are given for practical evaluation of the electrocatalytic activity towards the BOR in three-electrode cell configuration. The major issue of gaseous hydrogen generation and escape upon DBFC operation is also addressed through a comprehensive review of various results depending on the anode composition. At last, preliminary concerns are raised about the stability of potential anode catalysts upon DBFC operation.

  14. First-principles investigations of ionic conduction in Li and Na borohydrides

    NASA Astrophysics Data System (ADS)

    Varley, Joel; Heo, Tae-Wook; Ray, Keith; Bonev, Stanimir; Wood, Brandon

    Recent experimental studies have identified a family of alkali borohydride materials that exhibit superionic transition temperatures approaching room temperature and ionic conductivities exceeding 0.1 S/cm-1, making them highly promising solid electrolytes for next-generation batteries. Despite the rapid advances in improving the superionic conductivity in these materials, an understanding of the exact mechanisms driving the transport remains unknown. Here we use ab initio molecular dynamics calculations to address this issue by characterizing the diffusivity of the Li and Na species in a representative set of closoborane ionic conductors. We investigate both the Na and Li-containing borohydrides with icosahedral (B12H12) and double-capped square antiprism (B10H10) anion species and discuss the trends in ionic conductivity as a function of stoichiometry and the incorporation of various dopants. Our results support the borohydrides as a subset of a larger family of very promising solid electrolytes and identify strategies to improving the conductivity in these materials. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  15. New direct 11B NMR-based analysis of organoboranes through their potassium borohydrides.

    PubMed

    Medina, Jesus R; Cruz, Gabriel; Cabrera, Carlos R; Soderquist, John A

    2003-06-13

    Representative organoborane mixtures were quantitatively converted to their borohydrides through their reaction with activated KH (KH), permitting their detailed analysis by (11)B NMR. Through the treatment of commercial KH with a THF solution of lithium aluminum hydride (LAH), a dramatic change in the surface morphology results as revealed by scanning electron microscopy (SEM). Energy dispersed spectroscopy (EDS) was employed to reveal that the LAH treatment deposits a significant amount of an unknown aluminum-containing species on the surface of the KH, which imparts a unique reactivity to the KH. Even highly hindered organoboranes are quantitatively converted to their borohydrides by replacing electronegative groups (e.g., OR, halogen) with hydrogen, retaining only the carbon ligation. Through this simple KH treatment, complex organoborane reaction mixtures are converted to the corresponding borohydrides whose (11)B NMR spectra normally exhibit resolved signals for the individual species present. The integration of these signals provides quantitative information on the relative amounts of each component of the mixture. New generalities for the effect of alpha-, beta-, and gamma-substituents have also been determined that provide a new, simple technique for the determination of the isomeric distribution in organoborane mixtures resulting from common organoborane processes (e.g., hydroboration). Moreover, the (1)H-coupled (11)B NMR spectra of these mixtures reveal the extent of alkylation for each species present. Representative organoboranes were examined by this new technique permitting a simple and convenient quantitative analysis of the regio- and diastereomeric composition of a variety of asymmetric organoborane processes. Previously unknown details of pinene-based hydroborations and reductions are revealed for the first time employing the KH (11)B NMR technique. PMID:12790565

  16. Heavy metal removal by chemical reduction with sodium borohydride. A pilot-plant study

    SciTech Connect

    Gomez-Lahoz, C.; Garcia-Herruzo, F.; Rodriguez-Maroto, J.M.; Rodriguez, J.J. )

    1992-10-01

    A 1,000/h continuous pilot-plant study dealing with Cu{sup 2+} and Co{sup 2+} removal from simulated industrial wastewater by means of chemical reduction with sodium borohydride is presented. Initial metal concentrations in the 25 to 40 mg range have been tested. Residual concentrations lower than 0.1 mg have been achieved when operating under optimal conditions. Prior addition of sodium dithionite was required to avoid reoxidation problems arising from dissolved oxygen. Flocculation-sedimentation and sand filtration have been studied for sludge separation.

  17. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes

    PubMed Central

    2015-01-01

    The 15e square-planar complexes [Co(PCPMe-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Co(PCP-tBu)(η2-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η2-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d7 low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCPMe-iPr)(η2-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCPMe-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCPMe-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η2-mode. [Ni(PCPMe-iPr)(η2-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of 1H, 13C{1H}, and 31P{1H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCPMe-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Ni(PCPMe-iPr)(η2-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCPMe-iPr)H] and [Ni(PCPMe-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and the bonding of the borohydride ligand in [Co

  18. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    SciTech Connect

    Sadikin, Yolanda; Stare, Katarina; Schouwink, Pascal; Brix Ley, Morten; Jensen, Torben R.; Meden, Anton; Černý, Radovan

    2015-05-15

    The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y{sup 3+} is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH{sub 4} both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A{sub 3}Y(BH{sub 4}){sub 6} or c-A{sub 2}LiY(BH{sub 4}){sub 6} (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH{sub 4}){sub 4} crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y{sup 3+} is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH{sub 4}){sub 4} structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH{sub 4} (A=K, Rb, Cs) contains nine compounds in total. • Y{sup 3+} forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH{sub 4}){sub 4} crystallize with

  19. The borohydride oxidation reaction on La-Ni-based hydrogen-storage alloys.

    PubMed

    Paschoalino, Waldemir J; Thompson, Stephen J; Russell, Andrea E; Ticianelli, Edson A

    2014-07-21

    This work provides insights into the processes involved in the borohydride oxidation reaction (BOR) in alkaline media on metal hydride alloys formed by LaNi(4.7)Sn(0.2)Cu(0.1) and LaNi(4.78)Al(0.22) with and without deposited Pt, Pd, and Au. The results confirm the occurrence of hydrolysis of the borohydride ions when the materials are exposed to BH(4)(-) and a continuous hydriding of the alloys during BH(4)(-) oxidation measurements at low current densities. The activity for the direct BOR is low in both bare metal hydride alloys, but the rate of the BH(4)(-) hydrolysis and the hydrogen-storage capacity are higher, while the rate of H diffusion is slower for bare LaNi(4.78) Al(0.22). The addition of Pt and Pd to both alloys results in an increase of the BH(4)(-) hydrolysis, but the H(2) formed is rapidly oxidized at the Pt-modified catalysts. In the case of Au modification, a small increase in the BH(4)(-) hydrolysis is observed as compared to the bare alloys. The presence of Au and Pd also leads to a reduction of the rates of alloy hydriding/de-hydriding. PMID:24700670

  20. High performance and eco-friendly chitosan hydrogel membrane electrolytes for direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Choudhury, Nurul A.; Ma, Jia; Sahai, Yogeshwar

    2012-07-01

    Novel, cost-effective, and environmentally benign polymer electrolyte membranes (PEMs) consisting of ionically cross-linked chitosan (CS) hydrogel is reported for direct borohydride fuel cells (DBFCs). The membranes have been prepared by ionic cross-linking of CS with sulfate and hydrogen phosphate salts of sodium. Use of Na2SO4 and Na2HPO4 as cross-linking agents in the preparation of ionically cross-linked CS hydrogel membrane electrolytes (ICCSHMEs) not only enhances cost-effectiveness but also environmental friendliness of fuel cell technologies. The DBFCs have been assembled with a composite of nickel and carbon-supported palladium as anode catalyst, carbon-supported platinum as cathode catalyst and ICCSHMEs as electrolytes-cum-separators. The DBFCs have been studied by using an aqueous alkaline solution of sodium borohydride as fuel in flowing mode using a peristaltic pump and oxygen as oxidant. A maximum peak power density of about 810 mW cm-2 has been achieved for the DBFC employing Na2HPO4-based ICCSHME and operating at a cell temperature of 70 °C.

  1. Improvement of the periodate-borohydride surface-labeling method for human blood platelets

    SciTech Connect

    Steiner, B.; Clemetson, K.J.; Luescher, E.F.

    1983-01-01

    The periodate/sodium boro(/sup 3/H)hydride ((/sup 3/H)-NaBH4) method is extensively used for the specific labeling of cell surface glycoproteins. Reduction with tritiated borohydride is also used in other surface-labeling techniques, the neuraminidase/galactose oxidase/(/sup 3/H)-NaBH4 method (specific for terminal galactose and N-acetyl-galactosamine residues) and the pyridoxal phosphate/(/sup 3/H)-NaBH4 method (specific for protein). By modification of the reaction conditions during the periodate-oxidation and borohydride-reduction, the ratio of the incorporated to the total added radioactivity could be increased by a factor of 50, while the specific activity of the labeled material was twice as high as in the original method. Alternatively, by another modification, the specific activity of the labeled material could be increased about 10-fold. The influence of the most important parameters was investigated in detail. Sodium dodecyl sulfate gel electrophoresis and fluorography demonstrate that the labeling pattern of the membrane glycoproteins is the same as with the conventional method.

  2. Novel sodium aluminium borohydride containing the complex anion [Al(BH4,Cl)4]-.

    PubMed

    Lindemann, Inge; Ferrer, Roger Domènech; Dunsch, Lothar; Cerný, Radovan; Hagemann, Hans; D'Anna, Vincenza; Filinchuk, Yaroslav; Schultz, Ludwig; Gutfleisch, Oliver

    2011-01-01

    The synthesis of a novel alkali-metal aluminium borohydride NaAl(BH4)xCl4-x from NaBH4 and AlCl3 using a solid state metathesis reaction is described. Structure determination was carried out using synchrotron powder diffraction data and vibrational spectroscopy. An orthorhombic structure (space group Pmn2(1)) is formed which contains Na+ cations and complex [Al(BH4,Cl)4]- anions. Due to the high chlorine content (1 < or = x < or = 1.43) the hydrogen density of the borohydride is only between 2.3 and 3.5 wt.% H2 in contrast to the expected 14.6 wt.% for chlorine free NaAl(BH4)4. The decomposition of NaAl(BH4)xCl4-x is observed in the target range for desorption at about 90 degrees C by differential scanning calorimetry (DSC), in situ Raman spectroscopy and synchrotron powder X-ray diffraction. Thermogravimetric analysis (TG) shows extensive mass loss indicating the loss of H2 and B2H6 at about 90 degrees C followed by extensive weight loss in the form of chloride evaporation. PMID:22455071

  3. Spectroscopic study of surface enhanced Raman scattering of caffeine on borohydride-reduced silver colloids

    NASA Astrophysics Data System (ADS)

    Chen, Xiaomin; Gu, Huaimin; Shen, Gaoshan; Dong, Xiao; Kang, Jian

    2010-06-01

    The surface enhanced Raman scattering (SERS) of caffeine on borohydride-reduced silver colloids system under different aqueous solution environment has been studied in this paper. The relative intensity of SERS of caffeine significantly varies with different concentrations of sodium chloride and silver particles. However, at too high or too low concentration of sodium chloride and silver particle, the enhancement of SERS spectra is not evident. The SERS spectra of caffeine suggest that the contribution of the charge transfer mechanism to SERS may be dominant. The chloride ions can significantly enhance the efficiency of SERS, while the enhancement is selective, as the efficiency in charge transfer enhancement is higher than in electromagnetic enhancement. Therefore, it can be concluded that the active site of chloride ion locates on the bond between the caffeine and the silver surface. In addition, the SERS spectra of caffeine on borohydride-reduced and citrate-reduced silver colloids are different, which may be due to different states caffeine adsorbed on silver surface under different silver colloids.

  4. Electrocatalytic performance of Pt-Dy alloys for direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Šljukić, Biljana; Milikić, Jadranka; Santos, Diogo M. F.; Sequeira, César A. C.; Macciò, Daniele; Saccone, Adriana

    2014-12-01

    The electrochemical oxidation of sodium borohydride (NaBH4) is systematically studied on platinum-dysprosium (Pt-Dy) alloys in alkaline media with respect to application in direct borohydride fuel cells (DBFCs). Using several different techniques, namely cyclic voltammetry, chronoamperometry and chronopotentiometry, reaction parameters are evaluated for NaBH4 electrooxidation in 2 M NaOH supporting electrolyte. The values obtained for the number of electrons exchanged are comparable for the two alloys and close to 2.5. Dependence of Pt-Dy alloys activity for NaBH4 oxidation on the electrolyte composition and temperature is also investigated. Test fuel cell is assembled using Pt-Dy alloy as anode, reaching peak power density of 298 mW cm-2 at current density of 595 mA cm-2 and cell potential of 0.5 V at 25 °C. Pt-Dy alloys exhibit comparable behavior with pure Pt electrode at room temperature, while at higher temperature they exhibit improved Coulombic efficiency, with the advantage of significantly lower price.

  5. THE HYDROLYSIS AND OXIDATION BEHAVIOR OF LITHIUM BOROHYDRIDE AND MAGNESIUM HYDRIDE DETERMINED BY CALORIMETRY

    SciTech Connect

    Brinkman, K; Donald Anton, D; Joshua Gray, J; Bruce Hardy, B

    2008-03-13

    Lithium borohydride, magnesium hydride and the 2:1 'destabilized' ball milled mixtures (2LiBH{sub 4}:MgH{sub 2}) underwent liquid phase hydrolysis, gas phase hydrolysis and air oxidation reactions monitored by isothermal calorimetry. The experimentally determined heats of reaction and resulting products were compared with those theoretically predicted using thermodynamic databases. Results showed a discrepancy between the predicted and observed hydrolysis and oxidation products due to both kinetic limitations and to the significant amorphous character of observed reaction products. Gas phase and liquid phase hydrolysis were the dominant reactions in 2LiBH{sub 4}:MgH{sub 2} with approximately the same total energy release and reaction products; liquid phase hydrolysis displayed the maximum heat flow for likely environmental exposure with a peak energy release of 6 (mW/mg).

  6. A Study of the Combustion of Aluminum Borohydride in a Small Supersonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Allen, Harrison, Jr.; Fletcher, Edward A.

    1960-01-01

    The combustion of aluminum borohydride in the Mach 2 airstream of a 3.84- by 10-inch wind tunnel was studied by analyzing gas samples taken from the airstream. Gas mixture composition was determined with the aid of a vacuum apparatus and gas chromatograph. The overall combustion efficiency of the fuel was assumed to be good because the combustion efficiency of its hydrogen component was found to be high. The increase of the lateral surface area of the combustion region was dependent upon the degree of mixing of fuel and its combustion products with air. In the flame zone where there was insufficient oxygen for complete combustion, the metal components of the fuel appeared to burn preferentially to the hydrogen component.

  7. The removal of nitrate by nanoscale iron particles produced using the sodium borohydride method.

    PubMed

    Cho, Hyoung-Chan; Park, Sung Hoon; Ahn, Ho-Geun; Chung, Minchul; Kim, Byungwhan; Kim, Sun-Jae; Seo, Seong-Gyu; Jung, Sang-Chul

    2011-02-01

    This study was conducted to investigate removal of nitrate by nanoscale zero-valent iron (ZVI) particles in aqueous solution. ZVI particles was produced from wasted acid that is by-products of a pickling line at a steel work. The reaction activity of ZVI particles was evaluated through decomposition experiments of NO3-N aqueous solution. Addition of a larger amount of ZVI particles resulted in a higher decomposition rate. ZVI particles showed higher decomposition efficiencies than commercially purchased ZVI particles at all pH values. Both ZVIs showed a higher decomposition rate at a lower pH. Virtually no decomposition reaction was observed at pH of 4 or higher for purchased ZVI. The ZVI particles produced directly from wasted acid by the sodium borohydride method were not easy to handle because they were very small (10-200 nm) and were oxidized easily in the air. PMID:21456267

  8. The Discovery-Oriented Approach to Organic Chemistry. 6. Selective Reduction in Organic Chemistry: Reduction of Aldehydes in the Presence of Esters Using Sodium Borohydride

    ERIC Educational Resources Information Center

    Baru, Ashvin R.; Mohan, Ram S.

    2005-01-01

    A discovery-oriented lab experiment is developed that illustrates the chemoselective nature of reductions using sodium borohydride. Products are of sufficient purity to allow analysis by spectroscopy without further purification.

  9. Simultaneous desorption behavior of M borohydrides and Mg2FeH6 reactive hydride composites (M = Mg, then Li, Na, K, Ca)

    NASA Astrophysics Data System (ADS)

    Chaudhary, Anna-Lisa; Li, Guanqiao; Matsuo, Motoaki; Orimo, Shin-ichi; Deledda, Stefano; Sørby, Magnus H.; Hauback, Bjørn C.; Pistidda, Claudio; Klassen, Thomas; Dornheim, Martin

    2015-08-01

    Combinations of complex metal borohydrides ball milled with the transition metal complex hydride, Mg2FeH6, are analysed and compared. Initially, the Reactive Hydride Composite (RHC) of Mg2+ cation mixtures of Mg2FeH6 and γ-Mg(BH4)2 is combined in a range of molar ratios and heated to a maximum of 450 °C. For the molar ratio of 6 Mg2FeH6 + Mg(BH4)2, simultaneous desorption of the two hydrides occurred, which resulted in a single event of hydrogen release. This single step desorption occurred at temperatures between those of Mg2FeH6 and γ-Mg(BH4)2. Keeping this anionic ratio constant, the desorption behavior of four other borohydrides, Li-, Na-, K-, and Ca-borohydrides was studied by using materials ball milled with Mg2FeH6 applying the same milling parameters. The mixtures containing Mg-, Li-, and Ca-borohydrides also released hydrogen in a single event. The Mass Spectrometry (MS) results show a double step reaction within a narrow temperature range for both the Na- and K-borohydride mixtures. This phenomenon, observed for the RHC systems at the same anionic ratio with all five light metal borohydride mixtures, can be described as simultaneous hydrogen desorption within a narrow temperature range centered around 300 °C.

  10. Ultrafast and stable hydrogen generation from sodium borohydride in methanol and water over Fe-B nanoparticles

    NASA Astrophysics Data System (ADS)

    Ocon, Joey D.; Tuan, Trinh Ngoc; Yi, Youngmi; de Leon, Rizalinda L.; Lee, Jae Kwang; Lee, Jaeyoung

    2013-12-01

    Use of environmentally friendly hydrogen as fuel on a massive scale requires efficient storage and generation systems. Chemical hydrides, such as sodium borohydride (NaBH4), have the capacity to meet these needs as demonstrated by its high hydrogen storage efficiency. Here, we first report the catalytic activity of Fe-B nanoparticles supported on porous Ni foam - synthesized via a simple chemical reduction technique - for hydrogen generation from the mixtures of NaBH4, H2O, and CH3OH. Activation energies of the catalyzed hydrolysis (64.26 kJ mol-1) and methanolysis (7.02 kJ mol-1) are notably lower than other metal-boron catalysts previously reported. Methanol, in combination with a cheap but highly active Fe-B nanocatalysts, provides ultrafast rates of low temperature hydrogen generation from the sodium borohydride solutions.

  11. High volume hydrogen production from the hydrolysis of sodium borohydride using a cobalt catalyst supported on a honeycomb matrix

    NASA Astrophysics Data System (ADS)

    Marchionni, Andrea; Bevilacqua, Manuela; Filippi, Jonathan; Folliero, Maria G.; Innocenti, Massimo; Lavacchi, Alessandro; Miller, Hamish A.; Pagliaro, Maria V.; Vizza, Francesco

    2015-12-01

    Hydrogen storage and distribution will be two very important aspects of any renewable energy infrastructure that uses hydrogen as energy vector. The chemical storage of hydrogen in compounds like sodium borohydride (NaBH4) could play an important role in overcoming current difficulties associated with these aspects. Sodium borohydride is a very attractive material due to its high hydrogen content. In this paper, we describe a reactor where a stable cobalt based catalyst supported on a commercial Cordierite Honeycomb Monolith (CHM) is employed for the hydrolysis of alkaline stabilized NaBH4 (SBH) aqueous solutions. The apparatus is able to operate at up to 5 bar and 130 °C, providing a hydrogen generation rate of up to 32 L min-1.

  12. PtRu-LiCoO 2—an efficient catalyst for hydrogen generation from sodium borohydride solutions

    NASA Astrophysics Data System (ADS)

    Krishnan, Palanichamy; Yang, Tae-Hyun; Lee, Won-Yong; Kim, Chang-Soo

    Hydrogen generation by the hydrolysis of aqueous sodium borohydride (NaBH 4) solutions is studied using IRA-400 anion resin dispersed Pt, Ru catalysts and lithium cobalt oxide (LiCoO 2) supported Pt, Ru and PtRu catalysts. The performance of the LiCoO 2 supported catalysts is better than that of ion-exchange resin dispersed catalysts. There is a marked concentration dependence on the performance of the LiCoO 2 supported catalysts and the hydrogen generation rate decreases if the borohydride concentration is increased beyond 10 wt.%. The efficiency of PtRu-LiCoO 2 is almost double that of either Ru-LiCoO 2 or Pt-LiCoO 2 for NaBH 4 concentrations up to 10 wt.%.

  13. Mechanism and kinetics of sodium borohydride hydrolysis over crystalline nickel and nickel boride and amorphous nickel-boron nanoparticles

    NASA Astrophysics Data System (ADS)

    Wu, Zhijie; Mao, Xikang; Zi, Qin; Zhang, Rongrong; Dou, Tao; Yip, Alex C. K.

    2014-12-01

    The initial hydrogen generation turnover rates during the hydrolysis of sodium borohydride over nickel catalysts (crystalline nickel (Ni), crystalline nickel boride (Ni3B), and amorphous nickel-boron (Ni-B) nanoparticles) were measured to investigate the reaction kinetics and mechanisms by varying the reactant concentrations and reaction temperatures. Nickel catalysts with and without boron follow different hydrolysis pathways; hydroxide ions are involved in the activation of reactant molecules over Ni3B and Ni-B catalysts. This study explicitly reports the zero-order and first-order reaction kinetics with respect to the reactant concentration over Ni, Ni3B and Ni-B catalysts. The initial hydrogen generation turnover rates and activation energies determined from the experimental data indicate that the amorphous Ni-B nanoparticles exhibit the highest turnover rate and lowest activation energy for the hydrolysis of borohydride among the investigated catalysts. This study provides a general strategy for the development of borohydride hydrolysis catalysts via the modification of a metal catalyst using boron, which causes the crystalline structure to become amorphous and leads to electron-rich, highly undercoordinated metal atoms at the surface.

  14. Formation of borohydride-reduced nickel-boron coatings on various steel substrates

    NASA Astrophysics Data System (ADS)

    Vitry, V.; Delaunois, F.

    2015-12-01

    Electroless nickel-boron coatings are widely used in industrial on various substrates: ferrous and non-ferrous alloys mainly but also in some cases non-metallic materials. However, their growth process is still not fully understood and the influence of the nature of the substrate on this process is completely unknown. The formation of electroless nickel-boron was observed on five ferrous alloys: a mild steel, a high carbon unalloyed steel, a cryogenic steel (that contains 9 wt.% nickel), an austenitic stainless steel and an austeno-ferritic (duplex) stainless steel. Nickel-boron films were prepared by electroless deposition, using sodium borohydride as a reducing agent. Samples were immersed in a plating bath for times ranging from 5 s to 60 min. The influence of the nature of the substrate on the initial deposition of the coatings was investigated in detail: the initiation mechanism was identified for all substrates and it was found to be related to catalytic oxidation of the reducing agent rather than to a displacement process. The delay before initiation was influenced by the nickel content of the coating and by a high number of grain boundaries. In all cases, the plating rate varied with plating time, with a slower period during the first 10 min that corresponds to morphological modification of the coating.

  15. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

    NASA Astrophysics Data System (ADS)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-03-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution.

  16. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

    PubMed Central

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-01-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution. PMID:26980545

  17. Reductive reactivity of borohydride- and dithionite-synthesized iron-based nanoparticles: A comparative study.

    PubMed

    Ma, Xiaoming; He, Di; Jones, Adele M; Collins, Richard N; Waite, T David

    2016-02-13

    In this study sodium dithionite (NaS2O4) and sodium borohydride (NaBH4) were employed as reducing agents for the synthesis of nanosized iron-based particles. The particles formed using NaBH4 (denoted nFe(BH4)) principally contained (as expected) Fe(0) according to XAS and XRD analyses while the particles synthesized using NaS2O4, (denoted nFe(S2O4)) were dominated by the mixed Fe(II)/Fe(III) mineral magnetite (Fe3O4) though with possible presence of Fe(0). The ability of both particles to reduce trichloroethylene (TCE) under analogous conditions demonstrated remarkable differences with nFe(BH4) resulting in complete reduction of 1.5mM of TCE in 2h while nFe(S2O4) were unable to effect complete reduction of TCE in 120 h. Moreover, acetylene was the major reaction product formed in the presence of nFe(S2O4) while the major reaction product formed following reaction with nFe(BH4) was ethylene, which was further reduced to ethane as the reaction proceeded. Considering that effective Pd reduction to Pd(0) requires the presence of Fe(0), this is consistent with our finding that Fe(0) is not the dominant phase formed when employing dithionite as a reducing agent under the conditions employed in this study. PMID:26513569

  18. Investigation of carbon supported Pd-Cu nanoparticles as anode catalysts for direct borohydride fuel cell

    NASA Astrophysics Data System (ADS)

    Behmenyar, Gamze; Akın, Ayşe Nilgün

    2014-03-01

    Carbon supported Pd and bimetallic Pd-Cu nanoparticles with different compositions are prepared by a modified polyol method and used as anode catalysts for direct borohydride fuel cell (DBFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), ICP-AES, cyclic voltammetry (CV), chronoamperometry (CA), and fuel cell experiments. The results show that the carbon supported Pd-Cu bimetallic catalysts have much higher catalytic activity for the direct oxidation of BH4- than the carbon supported pure nanosized Pd catalyst, especially the Pd50Cu50/C catalyst presents the highest catalytic activity among all as-prepared catalysts, and the DBFC using Pd50Cu50/C as anode catalyst and Pt/C as cathode catalyst gives the best performance, and the maximum power density is 98 mW cm-2 at a current density of 223 mA cm-2 at 60 °C.

  19. Structure determination of ultra dense magnesium borohydride: A first-principles study

    NASA Astrophysics Data System (ADS)

    Fan, Jing; Duan, Defang; Jin, Xilian; Bao, Kuo; Liu, Bingbing; Cui, Tian

    2013-06-01

    Magnesium borohydride (Mg(BH4)2) is one of the potential hydrogen storage materials. Recently, two experiments [Y. Filinchuk, B. Richter, T. R. Jensen, V. Dmitriev, D. Chernyshov, and H. Hagemann, Angew. Chem., Int. Ed. 50, 11162 (2011);, 10.1002/anie.201100675 L. George, V. Drozd, and S. K. Saxena, J. Phys. Chem. C 113, 486 (2009), 10.1021/jp807842t] found that α-Mg(BH4)2 can irreversibly be transformed to an ultra dense δ-Mg(BH4)2 under high pressure. Its volumetric hydrogen content at ambient pressure (147 g/cm3) exceeds twice of DOE's (U.S. Department of Energy) target (70 g/cm3) and that of α-Mg(BH4)2 (117 g/cm3) by 20%. In this study, the experimentally proposed P42nm structure of δ-phase has been found to be dynamically unstable. A new Fddd structure has been reported as a good candidate of δ-phase instead. Its enthalpy from 0 to 12 GPa is much lower than P42nm structure and the simulated X-ray diffraction spectrum is in satisfied agreement with previous experiments. In addition, the previously proposed P-3m1 structure, which is denser than Fddd, is found to be a candidate of ɛ-phase due to the agreement of Raman shifts.

  20. Ultrahigh figure-of-merit for hydrogen generation from sodium borohydride using ternary metal catalysts

    NASA Astrophysics Data System (ADS)

    Hu, Lunghao; Ceccato, R.; Raj, R.

    We report further increase in the figure-of-merit (FOM) for hydrogen generation from NaBH 4 than reported in an earlier paper [1], where a sub-nanometer layer of metal catalysts are deposited on carbon nanotube paper (CNT paper) that has been functionalized with polymer-derived silicon carbonitride (SiCN) ceramic film. Ternary, Ru-Pd-Pt, instead of the binary Pd-Pt catalyst used earlier, together with a thinner CNT paper is shown to increase the figure-of-merit by up to a factor of six, putting is above any other known catalyst for hydrogen generation from NaBH 4. The catalysts are prepared by first impregnating the functionalized CNT-paper with solutions of the metal salts, followed by reduction in a sodium borohydride solution. The reaction mechanism and the catalyst efficiency are described in terms of an electric charge transfer, whereby the negative charge on the BH 4 - ion is exchanged with hydrogen via the electronically conducting SiCN/CNT substrate [1].

  1. High concentration magnesium borohydride/tetraglyme electrolyte for rechargeable magnesium batteries

    NASA Astrophysics Data System (ADS)

    Tuerxun, Feilure; Abulizi, Yasen; NuLi, Yanna; Su, Shuojian; Yang, Jun; Wang, JiuLin

    2015-02-01

    High concentration magnesium borohydride/tetraglyme electrolyte for rechargeable magnesium batteries is simply prepared by dissolving inorganic magnesium salt Mg(BH4) in tetraglyme (TG) ether solvent with good safety. 90 °C heating treatment is performed in the preparation process and LiBH4 as a chelating agent is added to improve the electrochemical performance. Mg deposition-dissolution performance and the electrochemical window of the electrolyte on non-inert stainless steel (SS), nickel (Ni), copper (Cu) electrodes and inert platinum (Pt) electrode are systematically studied by cyclic voltammetry and constant current discharge-charge measurements. 0.5 mol L-1 heated Mg(BH4)2/LiBH4/TG ([LiBH4] = 1.5 mol L-1) solution shows good electrochemical performance with 2.4 V (vs. Mg RE) anodic stability on stainless steel, close to 100% Mg deposition/dissolution efficiency and high cycling reversibility. Furthermore, the reversible electrochemical process of Mg intercalation into Mo6S8 cathode with excellent cycling performance in the electrolyte indicates the feasible application in rechargeable magnesium batteries.

  2. Investigation of the characteristics of a stacked direct borohydride fuel cell for portable applications

    NASA Astrophysics Data System (ADS)

    Kim, Cheolhwan; Kim, Kyu-Jung; Ha, Man Yeong

    To investigate the possibility of the portable application of a direct borohydride fuel cell (DBFC), weight reduction of the stack and high stacking of the cells are investigated for practical running conditions. For weight reduction, carbon graphite is adopted as the bipolar plate material even though it has disadvantages in tight stacking, which results in stacking loss from insufficient material strength. For high stacking, it is essential to have a uniform fuel distribution among cells and channels to maintain equal electric load on each cell. In particular, the design of the anode channel is important because active hydrogen generation causes non-uniformity in the fuel flow-field of the cells and channels. To reduce the disadvantages of stacking force margin and fuel maldistribution, an O-ring type-sealing system with an internal manifold and a parallel anode channel design is adopted, and the characteristics of a single and a five-cell fuel cell stack are analyzed. By adopting carbon graphite, the stack weight can be reduced by 4.2 times with 12% of performance degradation from the insufficient stacking force. When cells are stacked, the performance exceeds the single-cell performance because of the stack temperature increase from the reduction of the radiation area from the narrow stacking of cells.

  3. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions.

    PubMed

    Nayak, Nadiya B; Nayak, Bibhuti B

    2016-01-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution. PMID:26980545

  4. Ammine-Stabilized Transition-Metal Borohydrides of Iron, Cobalt, and Chromium: Synthesis and Characterization.

    PubMed

    Roedern, Elsa; Jensen, Torben R

    2015-11-01

    Iron and cobalt borohydrides stabilized by ammonia (NH3), [Fe(NH3)6](BH4)2 and [Co(NH3)6](BH4)2, were synthesized along with a solid solution, [Co(NH3)6](BH4)(2-x)Cl(x) (x ∼ 1), and a bimetallic compound, [Fe(NH3)6](Li2(BH4)4). The compounds were prepared by new low-temperature, solvent-based synthesis methods, using dimethyl sulfide or liquid NH3, which allow for the removal of inert metal halides. The crystal structures were determined from synchrotron radiation powder X-ray diffraction (SR-PXD) data. [M(NH3)6](BH4)2 (M = Fe, Co) and [Co(NH3)6](BH4)(2-x)Cl(x) crystallize in the cubic crystal system, where the transition metals are octahedrally coordinated by NH3. Polymeric chains of lithium coordinated by four bridging BH4(-) anions are found in [Fe(NH3)6](Li2(BH4)4). The new compounds have high hydrogen densities of ∼14 wt % H2 and ∼140 g H2/L and release a mixture of hydrogen and NH3 gas at low temperatures, T < 80 °C. The decomposition mechanisms of the prepared compounds along with the composites [Fe(NH3)6](BH4)2·nNH3BH3 (n = 2, 4, 6) were studied by thermal analysis and in situ SR-PXD. PMID:26488152

  5. (Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis.

    PubMed

    Schmid, Matthias; Oña-Burgos, Pascual; Guillaume, Sophie M; Roesky, Peter W

    2015-07-21

    The (iminophosphoranyl)(thiophosphoranyl)methanide {CH(PPh2=NSiMe3)(PPh2=S)}(-) ligand has been used for the synthesis of divalent and trivalent rare-earth borohydride complexes. The salt metathesis of the potassium reagent [K{CH(PPh2=NSiMe3)(PPh2=S)}]2 with [Yb(BH4)2(THF)2] resulted in the divalent monoborohydride ytterbium complex [{CH(PPh2=NSiMe3)(PPh2=S)}Yb(BH4)(THF)2]. The 2D (31)P/(171)Yb HMQC-NMR spectrum clearly showed the coupling between both nuclei. The trivalent bisborohydrides [{CH(PPh2=NSiMe3)(PPh2=S)}Ln(BH4)2(THF)] (Ln = Y, Sm, Tb, Dy, Er, Yb and Lu) were obtained by reaction of [K{CH(PPh2=NSiMe3)(PPh2=S)}]2 with [Ln(BH4)3(THF)3]. All new compounds were characterized by single X-ray diffraction. The divalent and trivalent compounds were next used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC). All complexes afforded a generally well-controlled ROP of both of these cyclic esters. High molar mass poly(ε-caprolactone) diols (Mn,NMR < 101,300 g mol(-1), ĐM = 1.44), and α,ω-dihydroxy and α-hydroxy,ω-formate telechelic poly(trimethylene carbonate)s (Mn,NMR < 20,000 g mol(-1), ĐM = 1.61) were thus synthesized under mild operating conditions. PMID:25683468

  6. Bis(phenolate)amine-supported lanthanide borohydride complexes for styrene and trans-1,4-isoprene (co-)polymerisations.

    PubMed

    Bonnet, Fanny; Dyer, Hellen E; El Kinani, Yassine; Dietz, Carin; Roussel, Pascal; Bria, Marc; Visseaux, Marc; Zinck, Philippe; Mountford, Philip

    2015-07-21

    New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2N(L) (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2N(L))(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2N(py))(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2N(L))(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2N(L))(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg((n)Bu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg((n)Bu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene. PMID:25997125

  7. Chiral Compounds and Green Chemistry in Undergraduate Organic Laboratories: Reduction of a Ketone by Sodium Borohydride and Baker's Yeast

    NASA Astrophysics Data System (ADS)

    Pohl, Nicola; Clague, Allen; Schwarz, Kimberly

    2002-06-01

    We describe an integrated set of experiments for the undergraduate organic laboratory that allows students to compare and contrast biological and chemical means of introducing chirality into a molecule. The racemic reduction of ethyl acetoacetate with sodium borohydride and the same reduction in the presence of a tartaric acid ligand are described, and a capillary gas chromatography column packed with a chiral material for product analysis is introduced. The results of these two hydride reactions are compared with the results of a common undergraduate experiment, the baker's yeast reduction of ethyl acetoacetate.

  8. Anodic behavior of carbon supported Cu@Ag core-shell nanocatalysts in direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Duan, Donghong; Liu, Huihong; You, Xiu; Wei, Huikai; Liu, Shibin

    2015-10-01

    Carbon-supported Cu@Ag core-shell nanoparticles are prepared by a successive reduction method in an aqueous solution and are used as an anode electrocatalyst for the direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), and fuel cell tests. In situ Fourier transform infrared (FTIR) spectroscopy is employed in 2 M NaOH/0.1 M NaBH4 to understand the borohydride oxidation reaction (BOR) mechanism by studying the intermediate reactions occurring on the Cu@Ag/C electrode. The TEM images show that the average size of the Cu1@Ag1/C particles is approximately 18 nm. Among the as-prepared catalysts, the Cu2@Ag1/C catalyst presents the highest catalytic activity. As shown by in situ FTIR, the oxidation reaction mechanism of BH4- is similar to that of Ag/C: BHn(OH)4-n- + 2OH- → BHn-1(OH)5-n- +H2 O + 2e . At 25 °C, the DBHFC with Cu2@Ag1/C as the anode electrocatalyst and Pt mesh (1 cm2) as the cathode electrode exhibits a maximum anodic power density of 17.27 mW mg-1 at a discharge current density of 27.8 mA mg-1.

  9. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

    PubMed Central

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-01-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications. PMID:27198738

  10. Zeolite-confined ruthenium(0) nanoclusters catalyst: record catalytic activity, reusability, and lifetime in hydrogen generation from the hydrolysis of sodium borohydride.

    PubMed

    Zahmakiran, Mehmet; Ozkar, Saim

    2009-03-01

    Sodium borohydride, NaBH4, has been considered the most attractive hydrogen-storage material for portable fuel cell applications, as it provides a safe and practical means of producing hydrogen. In a recent communication (Zahmakiran, M.; Ozkar, S. Langmuir 2008, 24, 7065), we have reported a record total turnover number (TTON) of 103 200 mol H2/mol Ru and turnover frequency (TOF) up to 33 000 mol H2/mol Ru x h obtained by using intrazeolite ruthenium(0) nanoclusters in the hydrolysis of sodium borohydride. Here we report full details of the kinetic studies on the intrazeolite ruthenium(0) nanoclusters catalyzed hydrolysis of sodium borohydride in both aqueous and basic solutions. Expectedly, the intrazeolite ruthenium(0) nanoclusters show unprecedented catalytic lifetime, TTON = 27 200 mol H2/mol Ru, and TOF up to 4000 mol H2/mol Ru x h in the hydrolysis of sodium borohydride in basic solution (5% wt NaOH) as well. More importantly, the intrazeolite ruthenium(0) nanoclusters are isolable, bottleable, redispersible, and yet catalytically active. They retain 76% or 61% of their initial catalytic activity at the fifth run with a complete release of hydrogen in aqueous and basic medium, respectively. The intrazeolite ruthenium(0) nanoclusters were isolated as black powder and characterized by using a combination of advanced analytical techniques including XRD, HRTEM, TEM-EDX, SEM, XPS, ICP-OES, and N2 adsorption. PMID:19437749

  11. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

    NASA Astrophysics Data System (ADS)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-05-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications.

  12. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders.

    PubMed

    Nayak, Nadiya B; Nayak, Bibhuti B

    2016-01-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications. PMID:27198738

  13. Electronic structure of nickel(II) and zinc(II) borohydrides from spectroscopic measurements and computational modeling.

    PubMed

    Desrochers, Patrick J; Sutton, Christopher A; Abrams, Micah L; Ye, Shengfa; Neese, Frank; Telser, Joshua; Ozarowski, Andrew; Krzystek, J

    2012-03-01

    The previously reported Ni(II) complex, Tp*Ni(κ(3)-BH(4)) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate anion), which has an S = 1 spin ground state, was studied by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy as a solid powder at low temperature, by UV-vis-NIR spectroscopy in the solid state and in solution at room temperature, and by paramagnetic (11)B NMR. HFEPR provided its spin Hamiltonian parameters: D = 1.91(1) cm(-1), E = 0.285(8) cm(-1), g = [2.170(4), 2.161(3), 2.133(3)]. Similar, but not identical parameters were obtained for its borodeuteride analogue. The previously unreported complex, Tp*Zn(κ(2)-BH(4)), was prepared, and IR and NMR spectroscopy allowed its comparison with analogous closed shell borohydride complexes. Ligand-field theory was used to model the electronic transitions in the Ni(II) complex successfully, although it was less successful at reproducing the zero-field splitting (zfs) parameters. Advanced computational methods, both density functional theory (DFT) and ab initio wave function based approaches, were applied to these Tp*MBH(4) complexes to better understand the interaction between these metals and borohydride ion. DFT successfully reproduced bonding geometries and vibrational behavior of the complexes, although it was less successful for the spin Hamiltonian parameters of the open shell Ni(II) complex. These were instead best described using ab initio methods. The origin of the zfs in Tp*Ni(κ(3)-BH(4)) is described and shows that the relatively small magnitude of D results from several spin-orbit coupling (SOC) interactions of large magnitude, but with opposite sign. Spin-spin coupling (SSC) is also shown to be significant, a point that is not always appreciated in transition metal complexes. Overall, a picture of bonding and electronic structure in open and closed shell late transition metal borohydrides is provided, which has implications for the use of these complexes in catalysis and

  14. Capacity enhancement of aqueous borohydride fuels for hydrogen storage in liquids

    SciTech Connect

    Schubert, David; Neiner, Doinita; Bowden, Mark; Whittemore, Sean; Holladay, Jamie; Huang, Zhenguo; Autrey, Tom

    2015-10-01

    In this work we demonstrate enhanced hydrogen storage capacities through increased solubility of sodium borate product species in aqueous media achieved by adjusting the sodium (NaOH) to boron (B(OH)3) ratio, i.e., M/B, to obtain a distribution of polyborate anions. For a 1:1 mole ratio of NaOH to B(OH)3, M/B = 1, the ratio of the hydrolysis product formed from NaBH4 hydrolysis, the sole borate species formed and observed by 11B NMR is sodium metaborate, NaB(OH)4. When the ratio is 1:3 NaOH to B(OH)3, M/B = 0.33, a mixture of borate anions is formed and observed as a broad peak in the 11B NMR spectrum. The complex polyborate mixture yields a metastable solution that is difficult to crystallize. Given the enhanced solubility of the polyborate mixture formed when M/B = 0.33 it should follow that the hydrolysis of sodium octahydrotriborate, NaB3H8, can provide a greater storage capacity of hydrogen for fuel cell applications compared to sodium borohydride while maintaining a single phase. Accordingly, the hydrolysis of a 23 wt% NaB3H8 solution in water yields a solution having the same complex polyborate mixture as formed by mixing a 1:3 molar ratio of NaOH and B(OH)3 and releases >8 eq of H2. By optimizing the M/B ratio a complex mixture of soluble products, including B3O3(OH)52-, B4O5(OH)42-, B3O3(OH)4-, B5O6(OH)4- and B(OH)3, can be maintained as a single liquid phase throughout the hydrogen release process. Consequently, hydrolysis of NaB3H8 can provide a 40% increase in H2 storage density compared to the hydrolysis of NaBH4 given the decreased solubility of sodium metaborate. The authors would like to thank Jim Sisco and Paul Osenar of

  15. Magnesium borohydride as a Hydrogen Stroage Materials: Properties and Dehydrogenation Pahtyway of Unsolvated Mg(BH4)2

    SciTech Connect

    Soloveichik, G.; Gao, Y; Rijssenbeek, J; Andrus, M; Kniajanski, S; Bowman Jr., R; Hwang, S; Zhao, J

    2009-01-01

    The decomposition of crystalline magnesium borohydride upon heating was studied using thermal desorption, calorimetry, in situ X-ray diffraction, and solid state NMR. Hydrogen release from Mg(BH4)2 occurs in at least four steps via formation of several polyborane intermediate species and includes an exothermic reaction yielding crystalline MgH2 as an intermediate. The decomposition products may be only partially recharged after the very first step and also via hydrogenation of Mg metal. The intermediate formation of amorphous MgB12H12, was confirmed by 11B NMR. A four-stage pathway for the thermal decomposition of Mg(BH4)2 is proposed.

  16. Borohydride ionic liquids and borane/ionic-liquid solutions as hypergolic fuels with superior low ignition-delay times.

    PubMed

    Li, Songqing; Gao, Haixiang; Shreeve, Jean'ne M

    2014-03-10

    In propellant systems, fuels of choice continue to be hydrazine and its derivatives, even though they comprise a class of acutely carcinogenic and toxic substances which exhibit rather high vapor pressures and require expensive handling procedures and costly safety precautions. Hypergolic ionic liquids tend to have low volatility and high thermal and chemical stability, and often exhibit wide liquid ranges, which could allow the use of these substances as bipropellant fuels under a variety of conditions. A new family of borohydride ionic liquids and borane-ionic-liquid solutions is described which meets nearly all of the desired important criteria for well-performing fuels. They exhibit ignition-delay times that are superior to that of any known hypergolic ionic liquid and may thus be legitimate replacements for hydrazine and its derivatives. PMID:24604814

  17. In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites.

    PubMed

    Miedema, Piter S; Ngene, Peter; van der Eerden, Ad M J; Sokaras, Dimosthenis; Weng, Tsu-Chien; Nordlund, Dennis; Au, Yuen S; de Groot, Frank M F

    2014-11-01

    Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de- and re-hydrogenation of nanoconfined lithium borohydride (LiBH4) and therefore we can possibly identify the de- and re-hydrogenation pathways. In the XRS of nanoconfined LiBH4 at different points in the de- and re-hydrogenation, we identified phases that lead to the conclusion that de- and re-hydrogenation pathways in nanoconfined LiBH4 are different from bulk LiBH4: intercalated lithium (LiCx), boron and lithium hydride were formed during de-hydrogenation, but as well Li2B12H12 was observed indicating that there is possibly some bulk LiBH4 present in the nanoconfined sample LiBH4-C as prepared. Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH4-C nanocomposites can be partially rehydrogenated to about 90% of Li2B12H12 and 2-5% of LiBH4 at a mild condition of 1 bar H2 and 350 °C. This suggests that re-hydrogenation occurs via the formation of Li2B12H12. Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications. PMID:25231357

  18. Borohydride complexes of europium(ii) and ytterbium(ii) and their conversion to metal borides. Structures of (l)4YbBh42 (L = Ch3Cn, C5H5N). (Reannouncement with new availability information)

    SciTech Connect

    White, J.P.; Deng, H.; Shore, S.G.

    1991-12-31

    Borohydride complexes of numerous metal ions are known. We have found that acetonitrile and pyridine are exceptionally good ligands for lathanide(II) ions. They promote formation of complexes with boron hydride and carborane anions. Use of these amines allows isolation of complexes that would otherwise be insoluble or unstable in other solvents. When these amines are employed as solvents, stable lanthanide(II) borohydride complexes can be isolated.

  19. Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH 4-air battery

    NASA Astrophysics Data System (ADS)

    Liu, B. H.; Li, Z. P.; Chen, L. L.

    In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH 4 gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH 4 concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl 2 catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH 4 gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH 4 solution. The NaBH 4 gel also successfully powered a NaBH 4-air battery.

  20. Investigation of platinum and palladium as potential anodic catalysts for direct borohydride and ammonia borane fuel cells

    NASA Astrophysics Data System (ADS)

    Olu, Pierre-Yves; Deschamps, Fabien; Caldarella, Giuseppe; Chatenet, Marian; Job, Nathalie

    2015-11-01

    Platinum and palladium are investigated as anodic catalysts for direct borohydride and direct ammonia borane fuel cells (DBFC and DABFC). Half-cell characterizations performed at 25 °C using NH3BH3 or NaBH4 alkaline electrolytes demonstrate the lowest open-circuit potential and highest electrocatalytic activity for the NH3BH3 alkaline electrolyte for Pd and Pt rotating disk electrodes, respectively. Voltammograms performed in fuel cell configuration at 25 °C confirm this trend: the highest open circuit voltage (1.05 V) and peak power density (181 mW·cm-2) are monitored for DABFC using Pd/C and Pt/C anodes, respectively. Increasing the temperature heightens the peak power density (that reaches 420 mW·cm-2 at 60 °C for DBFC using Pt/C anodes), but strongly generates gas from the fuel hydrolysis, hindering the overall fuel cells performances. The anode texture strongly influences the fuel cell performances, highlighting: (i) that an open anode texture is required to efficiently circulate the anolyte and (ii) the difficulty to compare potential anodic catalysts characterized using different fuel cell setups within the literature. Furthermore, TEM imaging of Pt/C and Pd/C catalysts prior/post DBFC and DABFC operation shows fast degradation of the carbon-supported nanoparticles.

  1. Which type of fuel cell is more competitive for portable application: Direct methanol fuel cells or direct borohydride fuel cells?

    NASA Astrophysics Data System (ADS)

    Wee, Jung-Ho

    The promise of fuel cell systems using liquid fuels, such as the direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), to complement or substitute for existing batteries is becoming recognized, along with their potential as a future technology for mobile and portable power supplies. The key issue is which type of fuel cell is more competitive for such power supplies: DMFC or DBFC? To answer this question, the present study analyzes and discusses the relative competitiveness of these two systems given the current status of the technologies and assuming some generally accepted conditions. The findings confirm that the DBFC system is superior to the DMFC system in terms of cell size and fuel (or fuel solution) consumption. Thus, the DBFC system is better suited to applications that require small operational space. On the other hand, the total operating costs of DBFC systems are higher than those of DMFC systems. According to the total cost formulae derived in the analysis, the DBFC system becomes relatively uneconomic at higher power outputs and longer operation times, but may be more favourable in specific portable applications such as miniaturized or micro power systems with short operational time spans.

  2. Enhanced activity of Au-Fe/C anodic electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

    NASA Astrophysics Data System (ADS)

    Yi, Lanhua; Wei, Wei; Zhao, Caixian; Tian, Li; Liu, Jing; Wang, Xianyou

    2015-07-01

    Carbon supported Au-Fe bimetallic nanocatalysts (Au-Fe/C) are facilely prepared via a modified NaBH4 reduction method in aqueous solution at room temperature, and used as the anode electrocatalyst of direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the Au-Fe/C electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), rotating disc electrode (RDE) voltammetry, chronoamperometry (CA), chronopotentiometry (CP), and fuel cell test. The results show that Au-Fe/C catalysts display higher catalytic activity for the direct electrooxidation of BH4- than carbon supported pure Au nanocatalyst (Au/C), especially Au50Fe50/C catalyst presents the highest catalytic activity among all as-prepared catalysts. Besides, the single DBHFC with Au50Fe50/C anode and Au/C cathode obtains the maximum power density as high as 34.9 mW cm-2 at 25 °C.

  3. The influence of LiH on the rehydrogenation behavior of halide free rare earth (RE) borohydrides (RE = Pr, Er).

    PubMed

    Heere, Michael; Payandeh GharibDoust, Seyed Hosein; Frommen, Christoph; Humphries, Terry D; Ley, Morten B; Sørby, Magnus H; Jensen, Torben R; Hauback, Bjørn C

    2016-09-21

    Rare earth (RE) metal borohydrides are receiving immense consideration as possible hydrogen storage materials and solid-state Li-ion conductors. In this study, halide free Er(BH4)3 and Pr(BH4)3 have been successfully synthesized for the first time by the combination of mechanochemical milling and/or wet chemistry. Rietveld refinement of Er(BH4)3 confirmed the formation of two different Er(BH4)3 polymorphs: α-Er(BH4)3 with space group Pa3[combining macron], a = 10.76796(5) Å, and β-Er(BH4)3 in Pm3[combining macron]m with a = 5.4664(1) Å. A variety of Pr(BH4)3 phases were found after extraction with diethyl ether: α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2465(1) Å, β-Pr(BH4)3 in Pm3[combining macron]m with a = 5.716(2) Å and LiPr(BH4)3Cl in I4[combining macron]3m, a = 11.5468(3) Å. Almost phase pure α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2473(2) Å was also synthesized. The thermal decomposition of Er(BH4)3 and Pr(BH4)3 proceeded without the formation of crystalline products. Rehydrogenation, as such, was not successful. However, addition of LiH promoted the rehydrogenation of RE hydride phases and LiBH4 from the decomposed RE(BH4)3 samples. PMID:27533740

  4. Quantitative Determination of Paraquat in Meconium by Sodium Borohydride-Nickel Chloride Chemical Reduction and Gas Chromatography/Mass Spectrometry (GC/MS)

    PubMed Central

    Posecion, Norberto C.; Ostrea, Enrique M.; Bielawski, Dawn M.

    2008-01-01

    The objective of this study was to develop a procedure for the GC/MS assay of paraquat in meconium as a biomarker of fetal exposure to paraquat. The method involved a sodium borohydride-nickel chloride reduction procedure, liquid-liquid extraction of the perhydrogenated product, concentration, and GC/MS assay. The method demonstrated good overall recovery (102.56 %) with %CV (inter-assay) of less than 13%, and a limit of detection of 0.0156 μg/g. Analysis of meconium samples from a study population in the Philippines (n = 70) showed a 2.8% prevalence of fetal exposure to paraquat. PMID:18037033

  5. Synthesis, structure and gas-phase reactivity of the mixed silver hydride borohydride nanocluster [Ag3(μ3-H)(μ3-BH4)LPh3]BF4 (LPh = bis(diphenylphosphino)methane)

    NASA Astrophysics Data System (ADS)

    Zavras, Athanasios; Ariafard, Alireza; Khairallah, George N.; White, Jonathan M.; Mulder, Roger J.; Canty, Allan J.; O'Hair, Richard A. J.

    2015-10-01

    Borohydrides react with silver salts to give products that span multiple scales ranging from discrete mononuclear compounds through to silver nanoparticles and colloids. The cluster cations [Ag3(H)(BH4)L3]+ are observed upon electrospray ionization mass spectrometry of solutions containing sodium borohydride, silver(i) tetrafluoroborate and bis(dimethylphosphino)methane (LMe) or bis(diphenylphosphino)methane (LPh). By adding NaBH4 to an acetonitrile solution of AgBF4 and LPh, cooled to ca. -10 °C, we have been able to isolate the first mixed silver hydride borohydride nanocluster, [Ag3(μ3-H)(μ3-BH4)LPh3]BF4, and structurally characterise it via X-ray crystallography. Combined gas-phase experiments (LMe and LPh) and DFT calculations (LMe) reveal how loss of a ligand from the cationic complexes [Ag3(H)(BH4)L3]+ provides a change in geometry that facilitates subsequent loss of BH3 to produce the dihydride clusters, [Ag3(H)2Ln]+ (n = 1 and 2). Together with the results of previous studies (Girod et al., Chem. - Eur. J., 2014, 20, 16626), this provides a direct link between mixed silver hydride/borohydride nanoclusters, silver hydride nanoclusters, and silver nanoclusters.Borohydrides react with silver salts to give products that span multiple scales ranging from discrete mononuclear compounds through to silver nanoparticles and colloids. The cluster cations [Ag3(H)(BH4)L3]+ are observed upon electrospray ionization mass spectrometry of solutions containing sodium borohydride, silver(i) tetrafluoroborate and bis(dimethylphosphino)methane (LMe) or bis(diphenylphosphino)methane (LPh). By adding NaBH4 to an acetonitrile solution of AgBF4 and LPh, cooled to ca. -10 °C, we have been able to isolate the first mixed silver hydride borohydride nanocluster, [Ag3(μ3-H)(μ3-BH4)LPh3]BF4, and structurally characterise it via X-ray crystallography. Combined gas-phase experiments (LMe and LPh) and DFT calculations (LMe) reveal how loss of a ligand from the cationic complexes [Ag

  6. Graphene-oxide-supported ultrathin Au nanowires: efficient electrocatalysts for borohydride oxidation† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5cc06705g Click here for additional data file.

    PubMed Central

    Leelavathi, Annamalai; Ahmad, Rafia; Singh, Abhishek K.; Madras, Giridhar

    2015-01-01

    We report stable ultrathin Au nanowires supported on reduced graphene oxide with outstanding electrocatalytic activity for borohydride oxidation. Electrochemical impedance spectroscopy measurements showed abnormal inductive behavior, indicative of surface reactivation. DFT calculations indicate that the origin of the high activity stems from the position of the Au d-band center. PMID:26439584

  7. Surface-enhanced Raman scattering study of riboflavin on borohydride-reduced silver colloids: Dependence of concentration, halide anions and pH values

    NASA Astrophysics Data System (ADS)

    Liu, Fangfang; Gu, Huaimin; Lin, Yue; Qi, Yajing; Dong, Xiao; Gao, Junxiang; Cai, Tiantian

    2012-01-01

    The influences of concentration, halide anions and pH on the surface-enhanced Raman scattering (SERS) of riboflavin adsorbed on borohydride-reduced silver colloids were studied. The optimum concentration for the SERS of riboflavin is 10 -6 mol/L while the SERS enhancement varies for different modes. The addition of 0.2 mol/L halide (NaCl, NaBr, and NaI) aqueous solutions, leads to a general decrease of the SERS intensity and a change of spectral profile of riboflavin excited at 514.5 nm. Riboflavin interacts with the silver surface possibly through the C dbnd O and N-H modes of the uracil ring. The SERS spectra of riboflavin were recorded in the 3.4-11.6 pH range. By analyzing several SERS marker bands, the protonated, deprotonated or the coexistence of both molecular species adsorbed on the colloidal silver particles was proved.

  8. Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane

    SciTech Connect

    Autrey, Thomas; Bowden, Mark E.; Karkamkar, Abhijeet J.

    2011-05-23

    Molecular complexes of Lewis acid-base pairs can be used to activate molecular hydrogen for applications ranging from hydrogen storage for fuel cells to catalytic hydrogenation reactions. In this paper, we examine the factors that determine the thermodynamics of hydrogen activation of a Lewis acid-base pair using the pedagogical examples of ammonia borane (NH3BH3, AB) and ammonium borohydride ([NH4][BH4], ABH2). At ambient temperatures, ABH2 loses hydrogen to form the Lewis acid-base complex AB, suggesting that free energy drives the reaction to release hydrogen. However, direct measurement of the reaction enthalpy is not straightforward given the complex decomposition pathways leading to the formation of the diammoniate of diborane ([NH3BH3NH3][BH4], DADB). In this work, we compare two approaches for deriving the thermodynamic relationships among AB, DADB, and ABH2.

  9. Structural analysis of some bis-(8-isopropyl-isoquinolinium) derivatives reveals a preferential folded conformation leading to a stereoselective attack by sodium borohydride

    NASA Astrophysics Data System (ADS)

    Dilly, Sébastien; Badarau, Eduard; Dufour, Fabien; Nistor, Iolanda; Hubert, Philippe; Seutin, Vincent; Wouters, Johan; Liégeois, Jean-François

    2014-09-01

    Reduction of symmetrical bis-isoquinolinium derivatives with sodium borohydride generates normally a mixture of three 1,2,3,4-tetrahydroisoquinoline stereoisomers. In a series of 8-isopropyl analogues, chiral resolution failed for the analogues with propyl and m-xylyl linkers since two and one peaks respectively were detected by HPLC. Further analysis by MS and CD of both peaks of the propyl analogue revealed that each peak corresponds to an enantiomer. Conformational analysis and X-ray cristallography showed a folded conformation of the propyl and m-xylyl analogues responsible for the observed stereoselectivity following the reduction step. Additional 1H NMR investigations confirm structural features detected by theoretical analysis.

  10. In situ synthesis of cobalt stabilized on macroscopic biopolymer hydrogel as economical and recyclable catalyst for hydrogen generation from sodium borohydride hydrolysis

    NASA Astrophysics Data System (ADS)

    Ai, Lunhong; Gao, Xiaoyan; Jiang, Jing

    2014-07-01

    In this study, we describe the successful fabrication of cobalt grown in situ on macroscopic alginate hydrogels (Co@AHs) and demonstrate that the as-prepared Co@AHs can act as a cost-effective and recyclable catalyst for hydrogen generation from the hydrolysis of NaBH4. The structure and morphology of the Co@AHs catalyst are identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The resultant Co@AHs samples show an excellent catalytic performance for the hydrogen generation from NaBH4 hydrolysis. The catalytic activity of the Co@AHs towards the hydrolysis reaction is systematically investigated by varying different reaction parameters, such as the catalyst dosage, temperature, and initial concentration of NaBH4 or NaOH. The Co@AHs catalyst can be easily separated after catalytic reaction and readily recycled over four successive reaction cycles. Considering that the eco-friendly and inexpensive Co@AHs is catalytically effective with superior recyclability, it should have potential application in the hydrogen generation from the hydrolysis of borohydrides.

  11. 10-methylacridine derivatives acting as efficient and stable photocatalysts in reductive dehalogenation of halogenated compounds with sodium borohydride via photoinduced electron transfer

    SciTech Connect

    Ishikawa, Masashi; Fukuzumi, Shunichi )

    1990-11-21

    10-Methylacridine derivatives, 9,10-dihydro-10-methylacridine (AcrH{sub 2}) and acriflavine (AFH{sup +}), act as efficient and stable photocatalysts in reductive dechlorination of p-chlorobiphenyl (ClBP) as well as dehalogenation of other halogenated compounds with sodium borohydride (NaBH{sub 4}) in a mixture of acetonitrile and H{sub 2}O (9:1 v/v) at 298 K. The reductive dechlorination proceeds via the reduction of ClBP by the singlet excited state ({sup 1}AcrH{sub 2}*) to yield dechlorinated product (biphenyl) and 10-methylacridinium ion (AcrH{sup +}), followed by the facile reduction of AcrH{sup +} with NaBH{sub 4} to regenerate AcrH{sub 2}. The absence of the primary kinetic isotope effect as well as the comparison of the observed rate constants with those predicted by using the Marcus theory of electron transfer indicates that the reduction of halogenated compounds (RX) by the singlet excited state ({sup 1}AcrH{sub 2}*) proceeds via photoinduced electron transfer from {sup 1}AcrH{sub 2}* to RX, which results in the cleavage of C-X bonds.

  12. Effects of washing solution and drying condition on reactivity of nano-scale zero valent irons (nZVIs) synthesized by borohydride reduction.

    PubMed

    Woo, Heesoo; Park, Junboum; Lee, Seockheon; Lee, Seunghak

    2014-02-01

    Washing and drying processes are essential when synthesizing nano-scale zero valent irons (nZVIs) by borohydride reduction of iron salts in aqueous phase. However, effects of these processes on nZVI reactivity have not been investigated in detail, although different washing and drying conditions might alter surface characteristics of nZVIs and thus vary their reactivity towards reducible contaminants. In this study, effects of three washing solutions and drying conditions on the reactivity of nZVIs for nitrate were investigated. Washing with volatile solvents and drying under anaerobic condition decreased thickness of Fe-oxide layer on nZVIs and increased content of Fe(2+)-containing oxides in the layer, which enhanced nZVI reactivity toward nitrate. Volatile solvent washing could minimize the decrease in nZVI reactivity according to changing anaerobic drying condition to aerobic. Findings from this study suggest that application of washing with volatile solvents and drying under aerobic condition should be recommended as effective processes to obtain nZVIs with maximum reactivity at reasonable costs and efforts. PMID:24290304

  13. Determination of inorganic mercury and total mercury in biological and environmental samples by flow injection-cold vapor-atomic absorption spectrometry using sodium borohydride as the sole reducing agent

    NASA Astrophysics Data System (ADS)

    Río Segade, Susana; Tyson, Julian F.

    2003-05-01

    A simple, fast, precise and accurate method to determine inorganic mercury and total mercury in biological and environmental samples was developed. The optimized flow-injection mercury system permitted the separate determination of inorganic mercury and total mercury using sodium borohydride as reducing agent. Inorganic mercury was selectively determined after reduction with 10 -4% w/v sodium borohydride, while total mercury was determined after reduction with 0.75% w/v sodium borohydride. The calibration graphs were linear up to 30 ng ml -1. The detection limits of the method based on three times the standard deviation of the blank were 24 and 3.9 ng l -1 for total mercury and inorganic mercury determination, respectively. The relative standard deviation was less than 1.5% for a 10 ng ml -1 mercury standard. As a means of checking method performance, deionized water and pond water samples were spiked with methylmercury and inorganic mercury; quantitative recovery for total mercury and inorganic mercury was obtained. The accuracy of the method was verified by analyzing alkaline and acid extracts of five biological and sediment reference materials. Microwave-assisted extraction procedures resulted in higher concentrations of recovered mercury species, lower matrix interference with mercury determination and less time involved in sample treatment than conventional extraction procedures. The standard addition method was only needed for calibration when biological samples were analyzed. The detection limits were in the range of 1.2-19 and 6.6-18 ng g -1 in biological and sediment samples for inorganic mercury and total mercury determination, respectively.

  14. Trends in Syntheses, Structures, and Properties for Three Series of Ammine Rare-Earth Metal Borohydrides, M(BH4)3·nNH3 (M = Y, Gd, and Dy).

    PubMed

    Jepsen, Lars H; Ley, Morten B; Černý, Radovan; Lee, Young-Su; Cho, Young Whan; Ravnsbæk, Dorthe; Besenbacher, Flemming; Skibsted, Jørgen; Jensen, Torben R

    2015-08-01

    Fourteen solvent- and halide-free ammine rare-earth metal borohydrides M(BH4)3·nNH3, M = Y, Gd, Dy, n = 7, 6, 5, 4, 2, and 1, have been synthesized by a new approach, and their structures as well as chemical and physical properties are characterized. Extensive series of coordination complexes with systematic variation in the number of ligands are presented, as prepared by combined mechanochemistry, solvent-based methods, solid-gas reactions, and thermal treatment. This new synthesis approach may have a significant impact within inorganic coordination chemistry. Halide-free metal borohydrides have been synthesized by solvent-based metathesis reactions of LiBH4 and MCl3 (3:1), followed by reactions of M(BH4)3 with an excess of NH3 gas, yielding M(BH4)3·7NH3 (M = Y, Gd, and Dy). Crystal structure models for M(BH4)3·nNH3 are derived from a combination of powder X-ray diffraction (PXD), (11)B magic-angle spinning NMR, and density functional theory (DFT) calculations. The structures vary from two-dimensional layers (n = 1), one-dimensional chains (n = 2), molecular compounds (n = 4 and 5), to contain complex ions (n = 6 and 7). NH3 coordinates to the metal in all compounds, while BH4(-) has a flexible coordination, i.e., either as a terminal or bridging ligand or as a counterion. M(BH4)3·7NH3 releases ammonia stepwise by thermal treatment producing M(BH4)3·nNH3 (6, 5, and 4), whereas hydrogen is released for n ≤ 4. Detailed analysis of the dihydrogen bonds reveals new insight about the hydrogen elimination mechanism, which contradicts current hypotheses. Overall, the present work provides new general knowledge toward rational materials design and preparation along with limitations of PXD and DFT for analysis of structures with a significant degree of dynamics in the structures. PMID:26196159

  15. Destabilization effect of transition metal fluorides on sodium borohydride.

    PubMed

    Kalantzopoulos, Georgios N; Guzik, Matylda N; Deledda, Stefano; Heyn, Richard H; Muller, Jiri; Hauback, Bjørn C

    2014-10-14

    The effect of transition metal fluorides on the decomposition of NaBH4 has been investigated for NaBH4 ball milled with TiF3, MnF3 or FeF3. The compounds were examined by thermal programmed desorption with residual gas analysis, thermo gravimetric analysis and volumetric measurements using a Sieverts-type apparatus. The phase formation process during thermal decomposition was studied by in situ synchrotron radiation powder X-ray diffraction on the as-milled powders. NaBF4 was among the products in all mechano-chemical reactions. (11)B-NMR spectra analysis gave NaBF4 : NaBH4 ratios of 1 : 150 for Na-Ti, 1 : 40 for Na-Mn, and 1 : 10 for Na-Fe. Pure NaBH4 possessed a hydrogen release onset temperature of 430 °C. The hydrogen release in the NaBH4-MnF3 system began as low as 130 °C. FeF3 decreased the onset temperature to 161 °C and TiF3 to 200 °C. TiF3 reacted completely with NaBH4 below 320 °C. All the examined systems have negligible emissions of diborane species. H-sorption studies performed at selected temperatures above 300 °C exhibited relatively fast desorption kinetics. Partial hydrogen re-absorption was observed for the Na-Mn and Na-Fe samples. PMID:25140831

  16. Copper removal from water by chemical reduction with sodium borohydride

    SciTech Connect

    Gomez-Lahoz, C.; Garcia-Herruzo, F.; Rodriguez-Maroto, J.M.; Rodriguez, J.J. )

    1992-09-01

    The use of NaBH{sub 4} as a chemical reductant to precipitate copper from water has been studied. Initial Cu{sup 2+} concentrations of 25 and 40 mg have been checked, and complete removal can be achieved. When solid NaBH{sub 4} is fed, BH{sub 4}{sup {minus}} to Cu{sup 2+} molar ratios higher than 2 were needed. This can be substantially improved by using NaBH{sub 4} as a stabilized alkaline solution. A kinetic model is proposed which gives information about the relative rates of the two competitive reactions involved (Cu{sup 2+} and water reduction with BH{sub 4}{sup {minus}}) and allows the operating conditions leading to minimum BH{sub 4}{sup {minus}} consumption to be established.

  17. Destabilized and catalyzed borohydride for reversible hydrogen storage

    DOEpatents

    Mohtadi, Rana F.; Nakamura, Kenji; Au, Ming; Zidan, Ragaiy

    2012-01-31

    A process of forming a hydrogen storage material, including the steps of: providing a first material of the formula M(BH.sub.4).sub.X, where M is an alkali metal or an alkali earth metal, providing a second material selected from M(AlH.sub.4).sub.x, a mixture of M(AlH.sub.4).sub.x and MCl.sub.x, a mixture of MCl.sub.x and Al, a mixture of MCl.sub.x and AlH.sub.3, a mixture of MH.sub.x and Al, Al, and AlH.sub.3. The first and second materials are combined at an elevated temperature and at an elevated hydrogen pressure for a time period forming a third material having a lower hydrogen release temperature than the first material and a higher hydrogen gravimetric density than the second material.

  18. Significantly enhanced dehydrogenation properties of calcium borohydride combined with urea.

    PubMed

    Chu, Hailiang; Qiu, Shujun; Liu, Lin; Zou, Yongjin; Xiang, Cuili; Zhang, Huanzhi; Xu, Fen; Sun, Lixian; Zhou, Huaiying; Wu, Guotao

    2014-11-01

    The interaction of [BH(x)]- and [NH(x)]-containing species gives rise to molecular hydrogen and the establishment of the B-N bond. Up to now, metal amides and ammonia are the commonly used [NH(x)] sources. Herein, urea, an organic carbonyl diamide, was used to react with Ca(BH4)2. A new type of complex hydride Ca(BH4)2·4CO(NH2)2 was synthesized with release of ca. 5.2 wt% hydrogen below 250 °C. PMID:25186984

  19. Borohydride electro-oxidation in a molten alkali hydroxide eutectic mixture and a novel borohydride-periodate battery

    NASA Astrophysics Data System (ADS)

    Wang, Andrew; Gyenge, Előd L.

    2015-05-01

    The electrochemical oxidation of BH4- in a molten NaOH-KOH eutectic mixture (0.515:0.485 mole fractions), is investigated for the first time by cyclic voltammetry and electrochemical impedance spectroscopy. Anodically oxidized Ni is electrocatalytically more active than Pt for BH4- oxidation in the molten alkali electrolyte as shown by the more than three times higher exchange current density (i.e. 15.8 mA cm-2 vs. 4.6 mA cm-2 at 185 °C). Next the proof-of-concept for a novel BH4-/IO4- molten alkali electrolyte battery is presented. Using oxidized Ni mesh anode and Pt mesh cathode a maximum power density of 63 mW cm-2 is achieved at 185 °C.

  20. Preparation, characterization and catalytic sodium borohydride hydrolysis of nanostructured cobalt-phosphorous catalysts

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Qi, Kezhen; Wu, Shiwei; Cao, Zhongqiu; Zhang, Ke; Lu, Yunshu; Liu, Hongxin

    2015-06-01

    In this paper, we report on the preparation, characterization and catalytic NaBH4 hydrolysis of nanostructured Co-P catalysts prepared using electroless plating method on the Cu sheet. Co-P catalysts composed of nanoplatelets, nanospheres and nanoflowers are successfully obtained by tuning the NaH2PO2 concentration. The as-prepared Co-P sample with hierarchical flower-like shape shows significantly enhanced catalytic activity during hydrolytic dehydrogenation of NaBH4, affording hydrogen release rate of 1647.9 mL min-1 g-1 at 30 °C and an activation energy of 47.0 kJ mol-1. This enhanced activity is due to their novel nanoflower architectures made up of nanoplatelets or the high surface roughness, providing many defects of angle, step, or edge and so on, to form more active sites on the catalyst surface. Furthermore, the hydrogen generation rate decreases gradually after 11 cycles, about 61% of the initial hydrogen generation rate. The study reveals the reason may be the decrease in the amount of P that provides active metallic Co sites on the catalyst surface.

  1. Synthesis of rock-salt type lithium borohydride and its peculiar Li+ ion conduction properties

    NASA Astrophysics Data System (ADS)

    Miyazaki, R.; Maekawa, H.; Takamura, H.

    2014-05-01

    The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH4, known for its super Li+ ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH4, more suitable to the high rate condition. We synthesized the H.P. form of LiBH4 under ambient pressure by doping LiBH4 with the KI lattice by sintering. The formation of a KI - LiBH4 solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li+ conductor despite its small Li+ content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the "Parasitic Conduction Mechanism." This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  2. Synthesis of rock-salt type lithium borohydride and its peculiar Li{sup +} ion conduction properties

    SciTech Connect

    Miyazaki, R.; Maekawa, H.; Takamura, H.

    2014-05-01

    The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH{sub 4,} known for its super Li{sup +} ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH{sub 4}, more suitable to the high rate condition. We synthesized the H.P. form of LiBH{sub 4} under ambient pressure by doping LiBH{sub 4} with the KI lattice by sintering. The formation of a KI - LiBH{sub 4} solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li{sup +} conductor despite its small Li{sup +} content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the “Parasitic Conduction Mechanism.” This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  3. The Reduction of a Nitrile (CN) Group by Sodium Borohydride. The Preparation of Phosphine--Amine and Phosphine--Iimidate Complesex of Tungsten Carbonyl.

    ERIC Educational Resources Information Center

    Faust, Kristen E.; Storhoff, Bruce N.

    1989-01-01

    Describes an experiment for advanced-level undergraduate students for extending student experiences involving recording and interpreting infrared (IR) and nuclear magnetic resonance (NMR) spectra from reactions of organometallic compounds. Experimental procedures, analyses and structural assignments, and suggestions for extension and modification…

  4. Metal-Borohydride-Modified Zr(BH4 )4 ⋅8 NH3 : Low-Temperature Dehydrogenation Yielding Highly Pure Hydrogen.

    PubMed

    Huang, Jianmei; Ouyang, Liuzhang; Gu, Qinfen; Yu, Xuebin; Zhu, Min

    2015-10-12

    Due to its high hydrogen density (14.8 wt %) and low dehydrogenation peak temperature (130 °C), Zr(BH4 )4 ⋅8 NH3 is considered to be one of the most promising hydrogen-storage materials. To further decrease its dehydrogenation temperature and suppress its ammonia release, a strategy of introducing LiBH4 and Mg(BH4 )2 was applied to this system. Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 composites showed main dehydrogenation peaks centered at 81 and 106 °C as well as high hydrogen purities of 99.3 and 99.8 mol % H2 , respectively. Isothermal measurements showed that 6.6 wt % (within 60 min) and 5.5 wt % (within 360 min) of hydrogen were released at 100 °C from Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 and Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , respectively. The lower dehydrogenation temperatures and improved hydrogen purities could be attributed to the formation of the diammoniate of diborane for Zr(BH4 )4 ⋅8 NH3 -4 LiBH4 , and the partial transfer of NH3 groups from Zr(BH4 )4 ⋅8 NH3 to Mg(BH4 )2 for Zr(BH4 )4 ⋅8 NH3 -2 Mg(BH4 )2 , which result in balanced numbers of BH4 and NH3 groups and a more active H(δ+) ⋅⋅⋅(-δ) H interaction. These advanced dehydrogenation properties make these two composites promising candidates as hydrogen-storage materials. PMID:26315468

  5. Pt-Sn/C catalysts prepared by sodium borohydride reduction for alcohol oxidation in fuel cells: Effect of the precursor addition order

    NASA Astrophysics Data System (ADS)

    López-Suárez, F. E.; Bueno-López, A.; Eguiluz, K. I. B.; Salazar-Banda, G. R.

    2014-12-01

    A series of Pt-Sn/C catalysts used as anodes during ethanol oxidation are synthesized by a deposition process using NaBH4 as the reducing agent. The order in which the precursors are added affects the electrocatalytic activity and physical-chemical characteristics of the bimetallic catalysts, where the Pt-Sn catalyst prepared by co-precipitation of both metals functions best below a potential of 0.5 V and the catalyst prepared by sequential deposition of Sn and Pt (drying after Sn addition) is most active above a potential of 0.5 V. The electrochemical behavior of catalysts during ethanol oxidation in an acidic medium are characterized and monitored in a half-cell test at room temperature by cyclic voltammetry, chronoamperometry and anode potentiostatic polarization. Catalyst structure and chemical composition are investigated by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This behavior presented for best Pt-Sn catalyst can be attributed to the so-called bifunctional mechanism and to the electronic interaction between Pt and Sn.

  6. Halide Free M(BH4)2 (M = Sr, Ba, and Eu) Synthesis, Structure, and Decomposition.

    PubMed

    Sharma, Manish; Didelot, Emilie; Spyratou, Alexandra; Lawson Daku, Latévi Max; Černý, Radovan; Hagemann, Hans

    2016-07-18

    Borohydrides have attained high interest in the past few years due to their high volumetric and gravimetric hydrogen content. Synthesis of di/trimetallic borohydride is a way to alter the thermodynamics of hydrogen release from borohydrides. Previously reported preparations of M(BH4)2 involved chloride containing species such as SrCl2. The presence of residual chloride (or other halide) ions in borohydrides may change their thermodynamic behavior and their decomposition pathway. Pure monometallic borohydrides are needed to study decomposition products without interference from halide impurities. They can also be used as precursors for synthesizing di/trimetallic borohydrides. In this paper we present a way to synthesize halide free alkaline earth metal (Sr, Ba) and europium borohydrides starting with the respective hydrides as precursors. Two novel high temperature polymorphs of Sr and Eu borohydrides and four polymorphs of Ba borohydride have been characterized by synchrotron X-ray powder diffraction, thermal analysis, and Raman and infrared spectroscopy and supported by periodic DFT calculations. The decomposition routes of these borohydrides have also been investigated. In the case of the decomposition of strontium and europium borohydrides, the metal borohydride hydride (M(BH4)H3, M = Sr, Eu) is observed and characterized. Periodic DFT calculations performed on room temperature Ba(BH4)2 revealed the presence of bidentate and tridentate borohydrides. PMID:27351948

  7. Process for synthesis of ammonia borane for bulk hydrogen storage

    SciTech Connect

    Autrey, S Thomas; Heldebrant, David J; Linehan, John C; Karkamkar, Abhijeet J; Zheng, Feng

    2011-03-01

    The present invention discloses new methods for synthesizing ammonia borane (NH.sub.3BH.sub.3, or AB). Ammonium borohydride (NH.sub.4BH.sub.4) is formed from the reaction of borohydride salts and ammonium salts in liquid ammonia. Ammonium borohydride is decomposed in an ether-based solvent that yields AB at a near quantitative yield. The AB product shows promise as a chemical hydrogen storage material for fuel cell powered applications.

  8. Chemiluminescence: An Illuminating Experiment

    ERIC Educational Resources Information Center

    Gafney, Harry D.; Adamson, Arthur W.

    1975-01-01

    Describes an experiment in which luminescence is observed during a reaction between sodium borohydride and trisbipyridalruthenium (III). Includes a discussion of the theory of chemiluminescence. (MLH)

  9. Regenerative Fuel Cells for Space Power and Energy Conversion (NaBH4/H2O2 Fuel Cell Development)

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas I.; Miley, George H.; Luo, Nie; Burton, Rodney; Mather, Joseph; Hawkins, Glenn; Byrd, Ethan; Gu, Lifeng; Shrestha, Prajakti Joshi

    2006-01-01

    A viewgraph presentation describing hydrogen peroxide and sodium borohydride development is shown. The topics include: 1) Motivation; 2) The Sodium Borohydride Fuel Cell; 3) Fuel Cell Comparisons; 4) MEA Optimization; 5) 500-Watt Stack Testing; 6) System Modeling: Fuel Cell Power Source for Lunar Rovers; and 7) Conclusions

  10. Hydrogen storage material and related processes

    DOEpatents

    Soloveichik, Grigorii Lev; Andrus, Matthew John

    2012-06-05

    Disclosed herein is a composition comprising a complex hydride and a borohydride catalyst wherein the borohydride catalyst comprises a BH.sub.4 group, and a group IV metal, a group V metal, or a combination of a group IV and a group V metal. Also disclosed herein are methods of making the composition.

  11. Hydrogen storage material and related processes

    DOEpatents

    Soloveichik; Grigorii Lev , Andrus; Matthew John

    2010-07-13

    Disclosed herein is a composition comprising a complex hydride and a borohydride catalyst wherein the borohydride catalyst comprises a BH.sub.4 group, and a group IV metal, a group V metal, or a combination of a group IV and a group V metal. Also disclosed herein are methods of making the composition.

  12. A Simple Recipe for Whitening Old Newspaper Clippings.

    ERIC Educational Resources Information Center

    Carter, Henry A.

    1995-01-01

    Describes a method for experimenting with both whitening and deacidifying old newspaper clippings using sodium borohydride bleaching. Clippings are soaked in distilled water then immersed in sodium borohydride for 15-20 minutes. After rinsing with distilled water, the paper is washed with saturated Ca(OH)2 solution. Readers should not begin…

  13. Metal-boride catalysts for indirect liquefaction. Quarterly technical progress report, December 1, 1982-February 28, 1983

    SciTech Connect

    Bartholomew, C.H.

    1983-03-15

    Four iron-boride catalysts were prepared. Washing with methanol did not change the iron phase composition as did water. Potassium borohydride reduction produces essentially the same iron phases as sodium borohydride reduction. Solution phase reductions with NH/sub 3/BH/sub 3/ were not productive. Reduction of ferric citrate with sodium borohydride produced a highly magnetic Fe/sub 2/B which was easily washed. Reduction of cobalt boride catalysts at a low temperature resulted in a catalyst with unusual selectivities in CO hydrogenation, i.e. the product contained more than 95% C/sub 5/-C/sub 16/ hydrocarbons. However, this catalyst deactivated rapidly.

  14. Reduction of. cap alpha. ,. beta. -unsaturated nitro compounds with boron hydrides: a new route to N-substituted hydroxylamines

    SciTech Connect

    Mourad, M.S.; Varma, R.S.; Kabalka, G.W.

    1985-01-11

    Sodium borohydride has been used to catalyze the reaction of borane complexes with alpha, beta-unsaturated nitroalkenes. The high purity hydroxylamines are readily isolated in high yield after hydrolysis. 12 references, 2 tables.

  15. Effects of the Reducing Agents on Morphologies of Gold Nanoparticles in POLY(STYRENE-B-4-VINYLPYRIDINE) Micelles

    NASA Astrophysics Data System (ADS)

    Ali, Nauman; Kim, Dong-Hun; Park, Lee-Soon; Kang, Inn-Kyu; Yoon, Keun-Byoung; Kwak, Giseop; Park, Soo-Young

    The effects of the reducing agents of hydrazine (H4N2), sodium borohydride (NaBH4), and triethylsilane (C6H15Si) on the morphologies of gold nanoparticles in the poly(styrene-b-4-vinylpyridine) micelle were studied using small-angle X-ray scattering (SAXS), UV/visible spectroscopy and transmission electron microscopy (TEM). "Cherry" morphology was found in the gold nanoparticles reduced by hydrazine while "raspberry" morphology was found in the gold nanoparticles reduced by sodium borohydride. Hydrazine was more effective in reducing gold nanoparticle in the core of the PS-b-P4VP micelle than sodium borohydride and triethylsilane. The nanoparticles reduced by hydrazine were confined in the core and more regular than those reduced by sodium borohydride and triethylsilane. The possible mechanism leading to these morphological differences was also discussed.

  16. Combustion of Various Highly Reactive Fuels in a 3.84- by 10-inch Mach 2 Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Allen, Harrison, Jr.; Fletcher, Edward A.

    1959-01-01

    The following fuels and fuel combinations injected from the top wall of a Mach 2 wind tunnel were successfully burned and gave associated pressure rises: aluminum borohydride, pentaborane, mixtures containing up to 41 percent JP-4 fuel in aluminum borohydride, tandem injections of aluminum borohydride, tandem injections of JP-4 fuel and aluminum borohydride, trimethyl aluminum with water injections, and diethyl aluminum hydride with water injections. The following fuels could not be ignited at the tunnel conditions (static pressure, 5.6 in. Hg; static temperature, -148 F): trimethylborane, triethylborane, propylpentaborane, ethyl- decaborane, and vinylsilane. Studies in which the heated region was probed by water injections indicated that the flow downstream of the flame front is subsonic and recirculating.

  17. Solid-state rechargeable magnesium battery

    DOEpatents

    Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

    2016-09-06

    Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

  18. Pathophysiology and toxicokinetic studies of blue-green algae intoxication in the swine model. Annual report, 1 September 1988-30 August 1989

    SciTech Connect

    Beasley, V.R.; Haschek-Hock, W.M.; Carmichael, W.M.; Cook, W.O.; Dahlem, A.M.

    1990-08-13

    Nonlabelled and tritium labelled dihydromicrocystin-LR (2H-MCLR) were produced by reacting MCLR with sodium borohydride and 3H-sodium borohydride, respectively. Chemical purity in excess of 99% and radiochemical purity of over 98% were demonstrated with TLC, HPLC, and mass spectrometry. The labelled toxin was stable for two wk in ethanol at -20C and significant, biological instability of the label was not apparent as indicated by the presence of tritiated water in urine of dosed animals.

  19. The effect of copper on iron reduction and its application to the determination of total iron content in iron and copper ores by potassium dichromate titration.

    PubMed

    Hu, Hanjun; Tang, Yang; Ying, Haisong; Wang, Minghai; Wan, Pingyu; Jin Yang, X

    2014-07-01

    The International Standard Organization (ISO) specifies two titrimetric methods for the determination of total iron content in iron ores using potassium dichromate as titrant after reduction of the iron(III) by tin(II) chloride and/or titanium(III) chloride. These two ISO methods (ISO2597-1 and ISO2597-2) require nearly boiling-point temperature for iron(III) reduction and suffer from copper interference and/or mercury pollution. In this study, potassium borohydride was used for reduction of iron(III) catalyzed by copper ions at ambient temperatures. In the absence of copper, iron(III) reduction by potassium borohydride was sluggish while a trace amount of copper significantly accelerated the reduction and reduced potassium borohydride consumption. The catalytic mechanism of iron(III) reduction in sulfuric acid and hydrochloric acid was investigated. Potassium borohydride in sodium hydroxide solution was stable without a significant degradation within 24h at ambient conditions and the use of potassium borohydride prepared in sodium hydroxide solution was safe and convenient in routine applications. The applicability of potassium borohydride reduction for the determination of total iron content by potassium dichromate titration was demonstrated by comparing with the ISO standard method using iron and copper ore reference materials and iron ore samples. PMID:24840467

  20. Mercury reduction studies to facilitate the thermal decontamination of phosphor powder residues from spent fluorescent lamps

    SciTech Connect

    Alves Durao, Walter; Andreva de Castro, Camila; Carvalhinho Windmoeller, Claudia

    2008-11-15

    This work investigates the thermal release of mercury from phosphor powder of spent fluorescent lamps. The treatment conditions and the ability of various reducing agents (primarily sodium borohydride) to lower the overall heating temperature required to improve the release of Hg have been evaluated. Hg species in samples were monitored in a thermal desorption atomic absorption spectrometer system, and total mercury was analyzed in a cold vapor atomic absorption spectrometer. Sodium borohydride was the best reducing agent among the ones studied. However, citric acid presented a high capacity to weaken mercury bonds with the matrix. When the sample was crushed with sodium borohydride for 40 min in a mass ratio of 10:1 (sample:reducing agent) and submitted to thermal treatment at 300 deg. C for 2 h, the concentration of mercury in a phosphor powder sample with 103 mg kg{sup -1} of mercury reached 6.6 mg kg{sup -1}.

  1. Method of synthesizing enriched decaborane for use in generating boron neutron capture therapy pharmaceuticals

    SciTech Connect

    Cowan, R.L.; Ginosar, D.M.; Dunks, G.B.

    2000-07-11

    A method is described for synthesizing decaborane where at least about 90% of the boron atoms in the decaborane are the {sup 10}B isotope, comprising the steps of: (a) reacting boric acid with a C(1) to C(10) alkanol to form a {sup 10}B-alkyl borate wherein at least about 90% of the boron atoms in the boric acid are the {sup 10}B isotope; (b) reducing the {sup 10}B-alkyl borate to form an alkali metal {sup 10}B-borohydride; (c) converting the alkali metal {sup 10}B-borohydride to a {sup 10}B-tetradecahydroundecaborate ion; and (d) converting the {sup 10}B-tetradecahydroundecaborate ion to {sup 10}B-decaborane. Methods of preparing tetradecahydroundecaborate ions and decaborane from alkali metal borohydrides are also described.

  2. Method of synthesizing enriched decaborane for use in generating boron neutron capture therapy pharmaceuticals

    SciTech Connect

    Cowan, Robert L.; Ginosar, Daniel M.; Dunks, Gary B.

    2000-01-01

    A method is described for synthesizing decaborane wherein at least about 90% of the boron atoms in the decaborane are the .sup.10 B isotope, comprising the steps of: (a) reacting boric acid with a C.sub.1 to C.sub.10 alkanol to form a .sup.10 B-alkyl borate wherein at least about 90% of the boron atoms in the boric acid are the .sup.10 B isotope; (b) reducing the .sup.10 B-alkyl borate to form an alkali metal .sup.10 B-borohydride; (c) converting the alkali metal .sup.10 B-borohydride to a .sup.10 B-tetradecahydroundecaborate ion; and (d) converting the .sup.10 B-tetradecahydroundecaborate ion to .sup.10 B-decaborane. Methods of preparing tetradecahydroundecaborate ions and decaborane from alkali metal borohydrides are also described.

  3. A new method for measuring degree of methyl esterification in pectin

    SciTech Connect

    Maness, N.O.; Ryan, J.D.; Mort, A.J. )

    1989-04-01

    A simple method to measure the degree of methyl esterification in small samples of pectins or isolated cell walls will be described. The method involves selective reduction of methyl esterified galacturonic acid to galactose with sodium borohydride or sodium borodeuteride in the presence of strong buffer at 4 C. Quantitative reduction of samples can be accomplished in 1 h using 20 mg borohydride per mg sample. The degree of pectin methyl esterification can then be determined by measuring an increase of galactose using gas chromatography (borohydride reduced samples) or gas chromatography/mass spectroscopy (borodeuteride reduced samples), or by measuring the decrease in galacturonic acid using conventional colorimetric methods. Pectin samples as small as 50 {mu}g have been analyzed using the reduction method with good results.

  4. Investigation of nanostructured platinum-nickel supported on the titanium surface as electrocatalysts for alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Tamašauskaitė-Tamašiūnaitė, L.; Balčiūnaitė, A.; Vaiciukevičienė, A.; Selskis, A.; Pakštas, V.

    2012-06-01

    This study involves the formation of nanostructured platinum-nickel supported on the titanium surface catalysts using the galvanic displacement technique and investigation of their electrocatalytic activity toward the oxidation of borohydride, methanol and ethanol in an alkaline media by cyclic voltammetry and chronoamperometry. Scanning electron microscopy, Energy Dispersive X-ray Spectroscopy and X-ray diffraction were used to characterize the surface structure, composition and morphology. The nanoPt(Ni)/Ti and nanoPt/Ti catalysts exhibited a higher catalytic efficiency to the oxidation of borohydride, ethanol and methanol as compared with that of pure Pt.

  5. Versatile, mild, and selective reduction of various carbonyl groups using an electron-deficient boron catalyst.

    PubMed

    Lucas, Katherine M; Kleman, Adam F; Sadergaski, Luke R; Jolly, Caitlyn L; Bollinger, Brady S; Mackesey, Brittany L; McGrath, Nicholas A

    2016-06-15

    A mild and selective new method was discovered to reduce acetanilides and other carbonyl compounds. Unlike sodium borohydride, which is selective in reducing aldehydes and ketones, this new protocol is uniquely selective in reducing acetanilides and nitriles over other carbonyl containing functional groups. Additionally, β-ketoamides were shown to be reduced at the ketone preferentially over the amide. PMID:27005847

  6. Highly Diastereoselective Synthesis of Tetrahydropyridines by a C–H Activation–Cyclization–Reduction Cascade

    PubMed Central

    Duttwyler, Simon; Lu, Colin; Rheingold, Arnold L.

    2012-01-01

    A versatile reaction cascade leading to highly substituted 1,2,3,6-tetrahydropyridines has been developed. It comprises rhodium(I)-catalyzed C–H activation–alkyne coupling followed by electrocyclization and subsequent acid/borohydride-promoted reduction. This one pot procedure affords the target compounds in up to 95% yields and with >95% diastereomeric purity. PMID:22356093

  7. Measurement of the Isotopic Ratio of [to the tenth power]B/[to the eleventh power]B in NaBH[subscript 4] by [to the first power]H NMR

    ERIC Educational Resources Information Center

    Zanger, Murray; Moyna, Guillermo

    2005-01-01

    A study uses nuclear magnetic resonance (NMR) spectroscopy in a novel way to determine the isotopic ration between [to the tenth power]B and [to the eleventh power]B in sodium borohydride (NaBH4). The experiment provides an unusual and relatively simple means for undergraduate chemistry students to accurately measure the distribution of the two…

  8. Platinum- and membrane-free swiss-roll mixed-reactant alkaline fuel cell.

    PubMed

    Aziznia, Amin; Oloman, Colin W; Gyenge, Előd L

    2013-05-01

    Eliminating the expensive and failure-prone proton exchange membrane (PEM) together with the platinum-based anode and cathode catalysts would significantly reduce the high capital and operating costs of low-temperature (<373 K) fuel cells. We recently introduced the Swiss-roll mixed-reactant fuel cell (SR-MRFC) concept for borohydride-oxygen alkaline fuel cells. We now present advances in anode electrocatalysis for borohydride electrooxidation through the development of osmium nanoparticulate catalysts supported on porous monolithic carbon fiber materials (referred to as an osmium 3D anode). The borohydride-oxygen SR-MRFC operates at 323 K and near atmospheric pressure, generating a peak power density of 1880 W m(-2) in a single-cell configuration by using an osmium-based anode (with an osmium loading of 0.32 mg cm(-2)) and a manganese dioxide gas-diffusion cathode. To the best of our knowledge, 1880 W m(-2) is the highest power density ever reported for a mixed-reactant fuel cell operating under similar conditions. Furthermore, the performance matches the highest reported power densities for conventional dual chamber PEM direct borohydride fuel cells. PMID:23589385

  9. Impregnated metal-polymeric functional beads

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Volksen, Willi (Inventor)

    1978-01-01

    Amine containing polymeric microspheres such as polyvinyl pyridine are complexed with metal salts or acids containing metals such as gold, platinum or iron. After reduction with sodium borohydride, the salt is reduced to finely divided free metal or metal oxides, useful as catalysts. Microspheres containing covalent bonding sites can be used for labeling or separating proteins.

  10. Impregnated metal-polymeric functional beads

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Amine containing polymeric microspheres such as polyvinyl pyridine are complexed with metal salts or acids containing metals such as gold, platinum or iron. After reduction with sodium borohydride, the salt is reduced to finely divided free metal or metal oxides, useful as catalysts. Microspheres containing covalent bonding sites can be used for labeling or separating proteins.

  11. DEMETALLATION OF USED OIL TO FACILITATE ITS UTILIZATION AS A FUEL

    EPA Science Inventory

    In the work, a chemical demetallation agent was used to convert entrained nonfilterable metals into a form which could be effectively removed by filtration. Two different types of chemical demetallation agents were used: metallic borohydrides (NaBHaub4 and KBHsub4) and diammonium...

  12. The characteristic red chemiluminescence from reactions with acidic potassium permanganate: further spectroscopic evidence for a manganese(II) emitter.

    PubMed

    Adcock, Jacqui L; Francis, Paul S; Smith, Trevor A; Barnett, Neil W

    2008-01-01

    A direct comparison of the laser-induced photoluminescence of manganese(ii) with the chemiluminescence from the reaction between acidic potassium permanganate and sodium borohydride was used to confirm that the characteristic red emission from this widely used chemiluminescence reagent emanates from an electronically excited manganese(ii) species. PMID:18087612

  13. Organosulphur compounds in coals as determined by reaction with Raney nickel and microscale pyrolysis techniques. Quarterly report, January 1, 1995--March 31, 1995

    SciTech Connect

    Philp, R.P.; Stalker, L.

    1995-09-01

    This report briefly descibes a method for cleaving organosulfur compounds from coal, kerogens and asphaltenes. The technique utilized nickel chloride and sodium borohydride. Experiments were performed on Illinois No. 6 coal. The method was also used in a deuterium labelling technique for investigating sulfur bonds.

  14. Experimental Microbiology of Saturated Salt Solutions and Other Harsh Environments. III. Growth of Salt-Tolerant Penicillium notatum in Boron-Rich Media 1

    PubMed Central

    Roberts, Karen; Siegel, S. M.

    1967-01-01

    A stress-tolerant strain of Penicillium notatum, isolated by passage through a nutrient solution saturated with calcium acetate, was found to have a tolerance to boron in several states of oxidation. Growth in the presence of elementary boron, saturating amounts of boric acid, and with various concentrations of sodium borohydride was observed and mycelial mats were spectrographically analyzed for boron accumulation. PMID:6076112

  15. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    EPA Science Inventory

    For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydro...

  16. Quantitative bioluminescent detection of bacteria

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Picciolo, G. L.

    1976-01-01

    Phosphoflavins in sample are measured using photobacterial luciferase assay technique for flavin mononucleotide (FMN). Boiling perchloric acid is used to rupture cells to free bound flavin and to hydrolyze flavin adenine dinucleotide to FMN. Base-stabilized water solution of sodium borohydride is used as reactant.

  17. In Situ NMR Study on the Interaction between LiBH4-Ca(BH4)2 and Mesoporous Scaffolds.

    PubMed

    Lee, Hyun-Sook; Hwang, Son-Jong; Kim, Hoon Kee; Lee, Young-Su; Park, Jinsol; Yu, Jong-Sung; Cho, Young Whan

    2012-10-18

    We discuss the use of nuclear magnetic resonance (NMR) spectroscopy to investigate the physical state of the eutectic composition of LiBH4-Ca(BH4)2 (LC) infiltrated into mesoporous scaffolds and the interface effect of various scaffolds. Eutectic melting and the melt infiltration of mixed borohydrides were observed through in situ NMR. In situ and ex situ NMR results for LC mixed with mesoporous scaffolds indicate that LiBH4 and Ca(BH4)2 exist as an amorphous mixture inside of the pores after infiltration. Surprisingly, the confinement of the eutectic LC mixture within the mesopores is initiated below the melting temperature, which indicates a certain interaction between the borohydrides and the mesoporous scaffolds. The confined borohydrides remain inside of the pores after cooling. These phenomena were not observed in microporous or nonporous materials, and this observation highlights the importance of the pore structure of the scaffolds. Such surface interactions may be associated with a faster dehydrogenation of the nanoconfined borohydrides. PMID:26292227

  18. Lewis base activation of borane-dimethylsulfide into strongly reducing ion pairs for the transformation of carbon dioxide to methoxyboranes.

    PubMed

    Légaré, Marc-André; Courtemanche, Marc-André; Fontaine, Frédéric-Georges

    2014-10-01

    The hydroboration of carbon dioxide into methoxyboranes by borane-dimethylsulfide using different base catalysts is described. A non-nucleophilic proton sponge is found to be the most active catalyst, with TOF reaching 64 h(-1) at 80 °C, and is acting via the activation of BH3·SMe2 into a boronium-borohydride ion pair. PMID:25164269

  19. NMR Studies of Structure-Reactivity Relationships in Carbonyl Reduction: A Collaborative Advanced Laboratory Experiment

    ERIC Educational Resources Information Center

    Marincean, Simona; Smith, Sheila R.; Fritz, Michael; Lee, Byung Joo; Rizk, Zeinab

    2012-01-01

    An upper-division laboratory project has been developed as a collaborative investigation of a reaction routinely taught in organic chemistry courses: the reduction of carbonyl compounds by borohydride reagents. Determination of several trends regarding structure-activity relationship was possible because each student contributed his or her results…

  20. Polyelectrolyte multilayered nanofilms as a novel approach for the protection of hydrogen storage materials.

    PubMed

    Borodina, T N; Grigoriev, D O; Andreeva, D V; Möhwald, H; Shchukin, D G

    2009-05-01

    This work describes the encapsulation of hydrogen storage materials from organic solvents. Due to complex formation the shell provides stability and selective permeability. Specifically, sodium borohydride particles were encapsulated within polymer films by the layer-by-layer self-assembly of oppositely charged polyelectrolytes (polyethyleneimine and poly(acrylonitrile-co-butadiene-co-acrylic acid)). The polymer nanofilm fabrication was performed using dichloromethane as a working media. IR spectroscopy was applied to investigate the chemical interaction between the polyelectrolytes. The multilayer film preparation was verified by Z-potential measurements, scanning electron microscopy, and confocal laser microscopy. The stability of sodium borohydride protected with a polyelectrolyte shell was increased compared to that of the pure material under ambient conditions. PMID:20355884

  1. Properties of amorphous FeCoB alloy particles (abstract)

    NASA Astrophysics Data System (ADS)

    Charles, S. W.; Wells, S.; Meagher, A.; Mørup, S.; van Wonterghem, J.

    1988-11-01

    Amorphous and crystalline alloy particles (0.05-0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x-ray diffraction. Magnetic measurements of the saturation magnetization, coercivity, and remanence of the particles have been measured. The transition from the amorphous-to-crystalline state has been studied using differential scanning calorimetry (DSC) and thermomagnetometry up to a temperature of 450 °C (see Fig. 1). It has been shown that the fraction of boron in the alloys (10-35 at. %) is dependent upon the rate of addition of salts to borohydride and the concentration of cobalt present; this in turn influences the crystallinity and magnetic properties .

  2. Nanosize cobalt boride particles: Control of the size and properties

    NASA Astrophysics Data System (ADS)

    Petit, C.; Pileni, M. P.

    1997-02-01

    Cobalt boride is obtained by the reduction of cobalt (2-ethyl hexyl) sulfosuccinate, Co(AOT) 2, by sodium borohydride either in reverse micelles or in a diphasic system. In Co(AOT) 2/Na(AOT)/H 2O reverse micellar solution, the size and polydispersity of the Co 2B particles is controlled by the size of the water droplets, which increases from 4 to 7.5 nm by increasing the water content. In a diphasic system of Co(AOT) 2/isooctane and sodium borohydride in aqueous solution, large and polydisperse particles of cobalt boride are formed (˜ 10 nm), and their magnetization properties are presented. The smallest particles are in a superparamagnetic regime at room temperature, whereas the largest particles show ferromagnetic behavior.

  3. A Novel One-Step Solvothermal Route to Nanocrystalline Sn 4P 3

    NASA Astrophysics Data System (ADS)

    Su, H. L.; Xie, Y.; Li, B.; Liu, X. M.; Qian, Y. T.

    1999-08-01

    A novel solvothermal method has been successfully developed to obtain nanocrystalline Sn4P3 in an autoclave based on the reaction of SnCl2 · 2H2O with yellow phosphorus at 160°C for 10 h, with potassium borohydride (KBH4) used as the reducing agent and ethanol as the solvent. XRD, TEM, and XPS examinations investigated the phase, grain size, morphology, and purity of the product, respectively. The product is spherical nanocrystalline Sn4P3 with a hexagonal structure. Potassium borohydride and ethanol played important roles in the formation of nanocrystalline Sn4P3. A possible mechanism is proposed as: under the solvothermal condition, Sn2+ was steadily reduced by KBH4 to atomic Sn; subsequently these newborn active atoms homogeneously combined with yellow phosphorus to form nanocrystalline Sn4P3.

  4. Preparation of Soft Magnetic Fe-Ni-Pb-B Alloy Nanoparticles by Room Temperature Solid-Solid Reaction

    PubMed Central

    Zhong, Qin

    2013-01-01

    The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g−1 is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed. PMID:24348196

  5. Uranium complexes with amide, alkoxide and thiolate ligands

    NASA Astrophysics Data System (ADS)

    Ephritikhine, Michel

    1994-10-01

    Alkoxide, hydroxide and mu-oxo complexes of U(IV) have been synthesized by (a) the reaction of alcohols, ketones and water with hydride or borohydride derivatives, (b) the coupling reaction of ketones with UCl4 in the presence of sodium amalgam; (c) the reduction of CO2 by (U(C5H4SiMe3)3) or (U(C5H4SiMe3)3H); (d) the deoxygenation of CO by (U(C5H5)3R) complexes; and (e) condensation reactions of alkoxide and hydroxide compounds. Thiolate complexes were made by the treatment of uranium borohydride or hydride compounds with thiols. The reaction of UCl4 with NaSR reagents afforded the homoleptic thiolate complexes ((THF)3Na(mu-SR)3U(mu-SR)3Na(THF)3). Amide compounds, including U(V) derivatives, were prepared from U(NEt 2)4.

  6. Dynamics of solvation and rotational relaxation of coumarin 480 in pure aqueous-AOT reverse micelle and reverse micelle containing different-sized silver nanoparticles inside its core: a comparative study.

    PubMed

    Setua, Palash; Ghatak, Chiranjib; Rao, Vishal Govind; Das, S K; Sarkar, Nilmoni

    2012-03-29

    In this work, we have synthesized different-sized silver nanoparticles in an aqueous-AOT reverse micellar system under the same condition by choosing different reduction processes. We chose two different reducing agents, glucose (mild) and sodium borohydride (strong). In the glucose reduction process, we obtained smaller size nanoparticles in comparison to the nanoparticles obtained in the borohydride reduction process under the same condition. Solvation dynamics study showed that reverse micellar aggregated structures were present after the nanoparticles' formation in a perturbed state. Nanoparticles inside the reverse micellar core were responsible for this perturbation. Larger size nanoparticles were triggering larger perturbation than the smaller size nanoparticles. These changes in perturbation were also reflected clearly in solvation dynamics and rotational relaxation measurements. PMID:22380919

  7. Preparation of soft magnetic Fe-Ni-Pb-B alloy nanoparticles by room temperature solid-solid reaction.

    PubMed

    Zhong, Guo-Qing; Zhong, Qin

    2013-01-01

    The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g(-1) is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed. PMID:24348196

  8. Characterization of a non-reducing terminal fragment from bovine articular cartilage keratan sulphates containing alpha(2-3)-linked sialic acid and alpha(1-3)-linked fucose. A sulphated variant of the VIM-2 epitope.

    PubMed Central

    Brown, G M; Huckerby, T N; Abram, B L; Nieduszynski, I A

    1996-01-01

    Alkaline-borohydride-reduced keratan sulphate chains were isolated from bovine articular cartilage (6-8-year-old animals) and digested with keratanase II, an endo- beta-N-acetylglucosaminidase. The resulting oligosaccharides were borohydride-reduced and fractionated on a strong anion-exchange column. 1H-NMR spectroscopic analysis of the products revealed one containing both alpha(2-3)-linked sialic acid and alpha(1-3)-linked fucose which was shown to have the structure (I) shown. This structure is a sulphated variant of the VIM-2 epitope (CD65), a putative ligand of E-selectin. No oligosaccharide containing the sialyl-Le(+) structure [NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-] was identified in this study. [equation: see text] PMID:8870660

  9. A novel magnetic Fe@Au core-shell nanoparticles anchored graphene oxide recyclable nanocatalyst for the reduction of nitrophenol compounds.

    PubMed

    Gupta, Vinod Kumar; Atar, Necip; Yola, Mehmet Lütfi; Üstündağ, Zafer; Uzun, Lokman

    2014-01-01

    In this study, a novel catalyst based on Fe@Au bimetallic nanoparticles involved graphene oxide was prepared and characterized by transmission electron microscope (TEM), and x-ray photoelectron spectroscopy (XPS). The nanomaterial was used in catalytic reductions of 4-nitrophenol and 2-nitrophenol in the presence of sodium borohydride. The experimental parameters such as temperature, the dosage of catalyst and the concentration of sodium borohydride were studied. The rates of catalytic reduction of the nitrophenol compounds have been found as the sequence: 4-nitrophenol>2-nitrophenol. The kinetic and thermodynamic parameters of nitrophenol compounds were determined. Activation energies were found as 2.33 kcal mol(-1) and 3.16 kcal mol(-1) for 4-nitrophenol and 2-nitrophenol, respectively. The nanomaterial was separated from the product by using a magnet and recycled after the reduction of nitrophenol compounds. The recyclable of the nanocatalyst is economically significant in industry. PMID:24112627

  10. Tailoring Thermodynamics and Kinetics for Hydrogen Storage in Complex Hydrides towards Applications.

    PubMed

    Liu, Yongfeng; Yang, Yaxiong; Gao, Mingxia; Pan, Hongge

    2016-02-01

    Solid-state hydrogen storage using various materials is expected to provide the ultimate solution for safe and efficient on-board storage. Complex hydrides have attracted increasing attention over the past two decades due to their high gravimetric and volumetric hydrogen densities. In this account, we review studies from our lab on tailoring the thermodynamics and kinetics for hydrogen storage in complex hydrides, including metal alanates, borohydrides and amides. By changing the material composition and structure, developing feasible preparation methods, doping high-performance catalysts, optimizing multifunctional additives, creating nanostructures and understanding the interaction mechanisms with hydrogen, the operating temperatures for hydrogen storage in metal amides, alanates and borohydrides are remarkably reduced. This temperature reduction is associated with enhanced reaction kinetics and improved reversibility. The examples discussed in this review are expected to provide new inspiration for the development of complex hydrides with high hydrogen capacity and appropriate thermodynamics and kinetics for hydrogen storage. PMID:26638824

  11. Synthesis of Substituted N-[4(5-Methyl/phenyl-1,3,4-oxadiazol-2-yl)-3,6-dihydropyridin-1(2H)-yl]benzamide/benzene Sulfonamides as Anti-Inflammatory and Anti-Cancer Agents

    PubMed Central

    Gangapuram, Madhavi; Redda, Kinfe K.

    2010-01-01

    Fourteen novel substituted N-[4(5-methyl/phenyl-1,3,4-oxadiazol-2-yl)-3,6-dihydropyridin-1(2H)-y1] benzamide/benzene sulfonamides (11a–n) were synthesized in fair to good yields via sodium borohydride reduction of the corresponding substituted N-(benzoylimino)-4-(5-methyl/5-phenyl-1,3,4-oxadiazol-2yl) pyridinium ylide (10a–n) in absolute ethanol. PMID:20526413

  12. Recent Progress in - and Nitrogen-Based Chemical Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Lu, Zhang-Hui; Xu, Qiang

    2012-03-01

    Boron- and nitrogen-based chemical hydrogen storage materials, such as metal borohydrides, ammonia borane, hydrazine borane, metal-nitrogen-hydrogen systems, ammonia, and hydrazine, have been extensively investigated in the past years. A variety of methods have been developed to decrease the reaction temperature and enhance the reaction kinetics of these systems. This feature article is to serve as an up to date account of the recent progress in chemical hydrogen storage with the boron- and nitrogen-based materials.

  13. Aerobic oxidation of anthracene in the presence of manganese porphyrinates and NaBH/sub 4/ reducing agent

    SciTech Connect

    Lukashova, E.A.; Solov'ev, A.B.; Chugreev, A.L.; Enikolopyan, N.S.

    1987-12-01

    The authors investigate the kinetics of anthracene oxidation by molecular oxygen in the presence of manganese, iron, and cobalt porphyrinate catalysts and a sodium borohydride reducing agent at room temperature in solutions of ethanol or ethanol with chloroform and benzene. Effective rate constants for the reactions are determined based on the amount of anthraquinone formed in the reaction. In all cases with the exception of cobalt tetraphenylporphyrinate the only oxidation product was anthraquinone. Its structure was verified by NMR and IR spectroscopy.

  14. A Study of Groundwater Matrix Effects for the Destruction of Trichloroethylene Using Fe/Pd Nanoaggregates

    SciTech Connect

    meyer, D E; Hampson, Steve; ormsbee, Lindelle; Bhattacharyya, Dibakar

    2008-06-01

    Fe nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-depostition. The Fe/Pd particles have been used to examine dechlorination of TCE with regard to matrix effects using materials representative of examine dechlorination of TCE with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah Gaseous Diffusion Plant in Paducah, KY.

  15. Rapid determination of nanogram amounts of tellurium in silicate rocks

    USGS Publications Warehouse

    Greenland, L.P.; Campbell, E.Y.

    1976-01-01

    A hydride-generation flameless atomic-absorption technique is used to determine as little as 5 ng g-1 tellurium in 0.25 g of silicate rock. After acid decomposition of the sample, tellurium hydride is generated with sodium borohydride and the vapor passed directly to a resistance-heated quartz cell mounted in an atomic-absorption spectrophotometer. Analyses of 11 U.S. Geological Survey standard rocks are presented. ?? 1976.

  16. Synthesis of Ca(BH4)2 from Synthetic Colemanite Used in Hydrogen Storage by Mechanochemical Reaction

    NASA Astrophysics Data System (ADS)

    Karabulut, Ahmet F.; Guru, Metin; Boynueğri, Tuğba A.; Aydin, Mustafa Yasir

    2016-05-01

    In this study, synthesis of Ca(BH4)2 has been carried out with a solid phase reaction in which synthetic colemanite has been used as a raw material. Three dimensional high energy spex collider was selected for this mechanochemical reaction. Calcium borohydride is one of the most valuable metal borohydrides. In order to produce calcium borohydride economically, anhydrous colemanite mineral has been used as reactant. Calcium borohydride has been directly manufactured from anhydrous colemanite in spex-type ball milling without the need for any intermediate product. Thus, the advantages of this method over wet chemical procedure (such as having no intermediate product, no azeotropic limitations and no need of regaining product from solution after production by using evaporation, crystallization and drying processes) have made it possible to achieve the desired economical gains. Parametric experiments were conducted to determine the best conditions for the highest yield of solid phase reaction in the spex-type ball milling. Best results have been determined by using areas of related peaks in spectra of Fourier transform infrared spectroscopy (FT-IR). In order to use peaks area for determining Ca(BH4)2 concentration, a calibration graph of FT-IR absorbance peak areas has been created by using samples with known different concentrations of commercial Ca(BH4)2. Optimum amounts of calcium hydride and synthesis reaction time were found to be 2.1 times the stoichiometric ratio and 2500 min, respectively. As a result of these optimizations, the maximum yield of the solid phase reaction carried out by the spex-type ball milling has been determined as 93%.

  17. Synthesis of Ca(BH4)2 from Synthetic Colemanite Used in Hydrogen Storage by Mechanochemical Reaction

    NASA Astrophysics Data System (ADS)

    Karabulut, Ahmet F.; Guru, Metin; Boynueğri, Tuğba A.; Aydin, Mustafa Yasir

    2016-08-01

    In this study, synthesis of Ca(BH4)2 has been carried out with a solid phase reaction in which synthetic colemanite has been used as a raw material. Three dimensional high energy spex collider was selected for this mechanochemical reaction. Calcium borohydride is one of the most valuable metal borohydrides. In order to produce calcium borohydride economically, anhydrous colemanite mineral has been used as reactant. Calcium borohydride has been directly manufactured from anhydrous colemanite in spex-type ball milling without the need for any intermediate product. Thus, the advantages of this method over wet chemical procedure (such as having no intermediate product, no azeotropic limitations and no need of regaining product from solution after production by using evaporation, crystallization and drying processes) have made it possible to achieve the desired economical gains. Parametric experiments were conducted to determine the best conditions for the highest yield of solid phase reaction in the spex-type ball milling. Best results have been determined by using areas of related peaks in spectra of Fourier transform infrared spectroscopy (FT-IR). In order to use peaks area for determining Ca(BH4)2 concentration, a calibration graph of FT-IR absorbance peak areas has been created by using samples with known different concentrations of commercial Ca(BH4)2. Optimum amounts of calcium hydride and synthesis reaction time were found to be 2.1 times the stoichiometric ratio and 2500 min, respectively. As a result of these optimizations, the maximum yield of the solid phase reaction carried out by the spex-type ball milling has been determined as 93%.

  18. Synthesis of octitols and the respective amino-derivatives from 'organo-aldols'.

    PubMed

    Łęczycka, Katarzyna; Chaciak, Bartosz; Cieplak, Maciej; Cmoch, Piotr; Jarosz, Sławomir

    2015-02-11

    Two diastereoisomeric keto-octoses, obtained in the reaction of 2,3:4,5-diacetone-D-arabinose with protected dihydroxyacetone catalyzed with L- or D-proline, were converted into octitols by stereoselective reduction of the carbonyl group with zinc borohydride and final deprotection. The study on the preparation of the respective amino-derivatives by reductive amination of these organo-adducts is presented; stereochemical aspects of these processes are discussed. PMID:25130931

  19. Investigation of the Coupled Effects of Molecular Weight and Charge-Transfer Interactions on the Optical and Photochemical Properties of Dissolved Organic Matter.

    PubMed

    McKay, Garrett; Couch, Kylie D; Mezyk, Stephen P; Rosario-Ortiz, Fernando L

    2016-08-01

    We studied the formation of photochemically produced reactive intermediates (RI) from dissolved organic matter (DOM). Specifically, we focused on the effects of variable molecular weight and chemical reduction on the optical properties of DOM (absorbance and fluorescence) and the formation of singlet oxygen ((1)O2), DOM triplet excited states ((3)DOM*), and the hydroxyl radical ((•)OH). The data are largely evaluated in terms of a charge-transfer (CT) model, but deficiencies in the model to explain the data are pointed out when evident. A total of two sets of samples were studied that were subjected to different treatments; the first set included secondary-treated wastewaters and a wastewater-impacted stream, and the second was a DOM isolate. Treatments included size fractionation and chemical reduction using sodium borohydride. Taken as a whole, the results demonstrate that decreasing molecular weight and borohydride reduction work in opposition regarding quantum efficiencies for (1)O2 and (3)DOM* production but in concert for fluorescence and (•)OH production. The optical and photochemical data provide evidence for a limited role of CT interactions occurring in lower-molecular-weight DOM molecules. In addition, the data suggest that the observed optical and photochemical properties of DOM are a result of multiple populations of chromophores and that their relative contribution is changed by molecular-weight fractionation and borohydride reduction. PMID:27377760

  20. Methods for preparation of extremely fine superalloy powders and fabrication to superalloy parts. Final report, October 1, 1995--February 15, 1998

    SciTech Connect

    Natesh, R.

    1998-07-01

    The use of reducing agents such as sodium borohydride have been used in a wide variety of chemical reactions from organic compounds synthesis to metal production. In order to reduce metal ions into the metallic state, the solution electrochemical potential must be sufficiently low to allow the metal to accept electrons from the reducing agent. One information source that gives important information regarding the conditions necessary for spontaneous aqueous nickel metal reduction is the electroless nickel plating literature. Although nickel is not the only desired metal, it provides an important starting point in metal reduction, and it is useful because of its resistance to corrosion. The electroless nickel plating literature indicates that sodium hypophosphite, sodium borohydride, and hydrazine are all used as reductants. Sodium hypophosphite is usually used at 30--95 C in a bath containing dissolved nickel sulfate and other additives such as oxalic acid and ammonium chloride. Sodium borohydride is usually used with sodium hydroxide in a similar temperature range. Hydrazine is also used with sodium hydroxide in a similar temperature range. However, in order to make the transition from electroless nickel deposition to spontaneous metal powder production requires different conditions. In this research program, a number of different conditions were examined to determine optimum conditions for the production of metal and metal alloy powders in aqueous solutions.

  1. Predicting new multicomponent materials for hydrogen storage using first-principles calculations

    NASA Astrophysics Data System (ADS)

    Aidhy, Dilpuneet; Wolverton, Chris

    2010-03-01

    Wide research has unraveled some very promising hydrogen storage materials such as metal borohydrides, amides and alanates. However, all of these materials are limited either thermodynamically or kinetically. The recent observation of mixing in these systems (e.g., borohydride-amide mixing in Li4(BH4)(NH2)3 [1] and metal mixing in NaZn2(BH4)3) [2] has demonstrated the possibility of forming new multicomponent ordered compounds that may have desirable hydrogen storage properties. However, these multicomponent systems are largely unexplored. Here, we use density functional theory (DFT) along with Monte Carlo-based crystal structure prediction methods to search for new multicomponent hydrides. We find evidence for stable compounds in the Mg(BH4)2/Mg(NH2)2 system, which have not yet been observed. In addition, we also study a wide range of mixed metal borohydride systems, and find evidence of ordered stable structures such as Li2Na(BH4)3. 1. F. E. Pinkerton, M. S. Meyer, G. P. Meisner and M. P. Balogh, J. Phys. Chem. B 110, 7967 (2006). 2. D. Ravnsbeak, Y. Filinchuk, Y. Cerenius, H. J. Jakobsen, F. Besenbacher, J. Skibsted and T. R. Jensen, Angew. Chem. 48, 6659 (2009).

  2. Synthesis of graphene platelets by chemical and electrochemical route

    SciTech Connect

    Ramachandran, Rajendran; Felix, Sathiyanathan; Joshi, Girish M.; Raghupathy, Bala P.C.; Jeong, Soon Kwan; Grace, Andrews Nirmala

    2013-10-15

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH{sub 4} was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide.

  3. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

  4. Compact solid source of hydrogen gas

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  5. Silver-colloid-nucleated cytochrome c superstructures encapsulated in silica nanoarchitectures.

    PubMed

    Wallace, Jean Marie; Dening, Brett M; Eden, Kristin B; Stroud, Rhonda M; Long, Jeffrey W; Rolison, Debra R

    2004-10-12

    We recently discovered that self-organized superstructures of the heme protein cytochrome c (cyt. c) are nucleated in buffer by gold nanoparticles. The protein molecules within the superstructure survive both silica sol-gel encapsulation and drying from supercritical carbon dioxide to form air-filled biocomposite aerogels that exhibit gas-phase binding activity for nitric oxide. In this investigation, we report that viable proteins are present in biocomposite aerogels when the nucleating metal nanoparticle is silver rather than gold. Silver colloids were synthesized via reduction of an aqueous solution of Ag+ using either citrate or borohydride reductants. As determined by transmission electron microscopy and UV-visible absorption spectroscopy, the silver nanoparticles vary in size and shape depending on the synthetic route, which affects the fraction of cyt. c that survives the processing necessary to form a biocomposite aerogel. Silver colloids synthesized via the citrate preparation are polydisperse, with sizes ranging from 1 to 100 nm, and lead to low cyt. c viability in the dried bioaerogels (approximately 15%). Protein superstructures nucleated at approximately 10-nm Ag colloids prepared via the borohydride route, including citrate stabilization of the borohydride-reduced metal, retain significant protein viability within the bioaerogels (approximately 45%). PMID:15461518

  6. Investigating the mechanism of phenol photooxidation by humic substances.

    PubMed

    Golanoski, Kelli S; Fang, Shuo; Del Vecchio, Rossana; Blough, Neil V

    2012-04-01

    To probe the mechanism of the photosensitized loss of phenols by humic substances (HS), the dependence of the initial rate of 2,4,6-trimethylphenol (TMP) loss (R(TMP)) on dioxygen concentration was examined both for a variety of untreated as well as borohydride-reduced HS and C(18) extracts from the Delaware Bay and Mid-Atlantic Bight. R(TMP) was inversely proportional to dioxygen concentration at [O(2)] > 50 μM, a dependence consistent with reaction with triplet excited states, but not with (1)O(2) or RO(2). Modeling the dependence of R(TMP) on [O(2)] provided rate constants for TMP reaction, O(2) quenching, and lifetimes compatible with a triplet intermediate. Borohydride reduction significantly reduced TMP loss, supporting the role of aromatic ketone triplets in this process. However, for most samples, the incomplete loss of sensitization following borohydride reduction, as well as the inverse dependence of R(TMP) on [O(2)] for these samples, suggests that there remains another class of oxidizing triplet sensitizer, perhaps quinones. PMID:22394372

  7. Studies on the solubilization of the water-insoluble fraction from human lens and cataract.

    PubMed

    Ortwerth, B J; Olesen, P R

    1992-12-01

    Studies were carried out comparing the ability of urea extraction and sonication to solubilize the water-insoluble (WI) protein fraction from human lens tissue. Sonication and urea extraction were able to solubilize greater than 80% of the insoluble protein whether whole lenses or lens nuclei were used. This was true for normal lens and +1 cataracts; however, only 60% solubilization was obtained with the WI fraction from more advanced cataracts. Equal aliquots of a WI fraction from both pooled normal and pooled cataract lens nuclei were solubilized with and without reducing agents. The addition of dithiothreitol (DTT) had no significant effect on solubilization of the normal lens WI fraction. DTT did increase the protein solubilized from the cataract WI fraction by 30% with urea extraction; however, no increase was seen with sonication. When sodium borohydride was used as the reducing agent, essentially the same results were obtained. The solubilized protein populations were identical by SDS-PAGE and amino acid analysis. The addition of reducing agents had no effect on the amino acid content of the solubilized proteins with the single exception of lysine. This amino acid was markedly decreased in the proteins extracted in the presence of 40 mM sodium borohydride, but not with DTT. These data suggest that the borohydride not only increased the amount of protein solubilized, but likely also stabilized glycated lysine residues during the acid hydrolysis. Therefore, sonication readily provides a soluble preparation of the WI proteins from normal and cataract lens nuclei without the need for denaturing agents, however, disulfide-linked and lysine modified crystallins were best solubilized with urea. PMID:1486936

  8. Core--strategy leading to high reversible hydrogen storage capacity for NaBH4.

    PubMed

    Christian, Meganne L; Aguey-Zinsou, Kondo-François

    2012-09-25

    Owing to its high storage capacity (10.8 mass %), sodium borohydride (NaBH(4)) is a promising hydrogen storage material. However, the temperature for hydrogen release is high (>500 °C), and reversibility of the release is unachievable under reasonable conditions. Herein, we demonstrate the potential of a novel strategy leading to high and stable hydrogen absorption/desorption cycling for NaBH(4) under mild pressure conditions (4 MPa). By an antisolvent precipitation method, the size of NaBH(4) particles was restricted to a few nanometers (<30 nm), resulting in a decrease of the melting point and an initial release of hydrogen at 400 °C. Further encapsulation of these nanoparticles upon reaction of nickel chloride at their surface allowed the synthesis of a core--shell nanostructure, NaBH(4)@Ni, and this provided a route for (a) the effective nanoconfinement of the melted NaBH(4) core and its dehydrogenation products, and (b) reversibility and fast kinetics owing to short diffusion lengths, the unstable nature of nickel borohydride, and possible modification of reaction paths. Hence at 350 °C, a reversible and steady hydrogen capacity of 5 mass % was achieved for NaBH(4)@Ni; 80% of the hydrogen could be desorbed or absorbed in less than 60 min, and full capacity was reached within 5 h. To the best of our knowledge, this is the first time that such performances have been achieved with NaBH(4). This demonstrates the potential of the strategy in leading to major advancements in the design of effective hydrogen storage materials from pristine borohydrides. PMID:22873406

  9. Manganese dioxide modified silicon nanowires and their excellent catalysis in the decomposition of methylene blue

    NASA Astrophysics Data System (ADS)

    Gao, Weiwei; Shao, Mingwang; Yang, Li; Zhuo, Shujuan; Ye, Shiyong; Lee, Shuit-tong

    2012-02-01

    A redox between hydrofluoric acid and ammonium fluoride-treated silicon nanowires and potassium permanganate solution was investigated. The results showed that MnO2 nanoparticles might grow on the surface of silicon nanowires, which was confirmed with the transmission electron microscope. These MnO2 modified silicon nanowires were employed as catalysts in the decomposition of methylene blue using sodium borohydride as the reducing agent, which exhibited excellent catalysis with its reaction rate 6 times larger than the unsupported MnO2.

  10. Immunochemical methods for quantitation of vitamin B6. Technical report

    SciTech Connect

    Brandon, D.L.; Corse, J.W.

    1981-09-30

    A procedure is described which proposes schemes for determining the total of all B6 vitamins in acid-hydrolyzed samples utilizing a radio-immunoassay (RIA) or an enzyme-immunoassay (EIA). Sample preparation is similar for both RIA and EIA. Two specific antibodies (antipyridoxine and antipyridoxamine) are employed to determine pyridoxamine, a portion of the sample is reduced with sodium borohydride. Pyridoxal is determined by difference between pyridoxine before and after reduction. The results indicate that two procedures have been developed which are selective for pyridoxamine (the fluorescent enzyme immunoassay and the spin immunoassay) and one assay which is equally sensitive to pyridoxine and pyridoxamine (the radio-immunoassay).

  11. A facile approach towards synthesis, characterization, single crystal structure, and DFT study of 5-bromosalicylalcohol

    NASA Astrophysics Data System (ADS)

    Rastogi, Rupali; Tarannum, Nazia; Butcher, R. J.

    2016-03-01

    5-Bromosalicylalcohol was prepared by the interaction of NaBH4 and 5-bromosalicylaldehyde. The use of sodium borohydride makes the reaction easy, facile, economic and does not require any toxic catalyst. The compound is characterized by FTIR, 1H NMR, 13C NMR, TEM and ESI-mass spectra. Crystal structure is determined by single crystal X-ray analysis. Quantum mechanical calculations of geometries, energies and thermodynamic parameters are carried out using density functional theory (DFT/B3LYP) method with 6-311G( d, p) basis set. The optimized geometrical parameters obtained by B3LYP method show good agreement with experimental data.

  12. One simple synthesis route to whisker-like nanocrystalline boron nitride by the reaction of NaBH{sub 4} and NaN{sub 3}

    SciTech Connect

    Ma Jianhua . E-mail: mjh820@ustc.edu; Li Jun; Li Guoxing; Tian Yiguang; Zhang Jing; Wu Jufeng; Zheng Jinyong; Zhuang Hemiao; Pan Tonghua

    2007-05-03

    Nanocrystalline boron nitride (BN) was synthesized via a simple route by the reaction of sodium borohydride with sodium azide in an autoclave at 600 deg. C. X-ray powder diffraction pattern indicated that the product was hexagonal BN, and the cell constant was a = 2.495 A, c = 6.687 A. Transmission electron microscopy image showed that it consisted of whisker-like particles with an average size of 200 nm x 20 nm. The product was also studied by FT-IR, XPS and TGA. It has good thermal stability and oxidation resistance in high temperature.

  13. Photochemical synthesis of Ag nanobars and their potential application as catalyst

    NASA Astrophysics Data System (ADS)

    Pyne, Santanu; Samanta, Sadhan; Misra, Ajay

    2013-12-01

    Monodispersed sodium alginate (SA) stabilized silver nano bar and hydroxyl propyl methyl cellulose (HPMC) stabilized silver nano bar have been synthesized by photochemical method. The nanoparticles are characterized by UV-VIS-NIR spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED) study. Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride in presence of nanoparticles is also evaluated. The kinetic data obtained by monitoring the change in UV-Vis absorption spectra of 4-NP are explained by Langmuir-Hinshelwood model. It is observed that the rate of reduction is higher in SA stabilized Ag nano bar than the HPMC stabilized Ag nano bar.

  14. Silver-coated monolithic columns for separation in radiopharmaceutical applications.

    PubMed

    Sedlacek, Ondrej; Kucka, Jan; Svec, Frantisek; Hruby, Martin

    2014-04-01

    In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In-house-prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m-iodobenzylguanidine labeled with radionuclide iodine-125. PMID:24478196

  15. Low-temperature approach to synthesize iron nitride from amorphous iron.

    PubMed

    Han, Yi; Wang, Huamin; Zhang, Minghui; Su, Ming; Li, Wei; Tao, Keyi

    2008-02-18

    Iron nitride was prepared by a nitridation reaction in NH 3 using amorphous iron as precursor. The precursor was prepared at ambient temperature through the process of reducing ferrous sulfate by potassium borohydride, followed by the nitridation at different temperatures. The nitridation reaction occurred at 548 K, and -Fe 2-3N was formed at 573 K. The reaction temperature was much lower than that using crystallized iron because of the characteristics of the amorphous materials. The existence of a small quantity of boron (1.6 wt.%) improved the stability of the amorphous precursor, which guaranteed an amorphous iron precursor at nitriding temperatures in excess of 548 K. PMID:18198828

  16. A simple route to Bi2Se3 and Bi2Te3 nanocrystals

    NASA Astrophysics Data System (ADS)

    Mntungwa, Nhlakanipho; Rajasekhar, Pullabhotla V. S. R.; Ramasamy, Karthik; Revaprasadu, Neerish

    2014-05-01

    Monodisperse nanocrystals of Bi2Se3 and Bi2Te3 capped with alkylamines have been synthesized via facile solution based method. The method involves reduction of selenium or tellurium using sodium borohydride, followed by thermolysis in an alkylamine at high temperature. Spherical shaped Bi2Se3 nanocrystals were obtained at 190 °C, whereas the reaction at 270 °C, yielded faceted nanocrystals. Similarly, spherical Bi2Te3 nanocrystals were obtained at all temperatures with hexadecylamine and oleylamine capping agents.

  17. Destruction of TCE Using Oxidative and Reductive Pathways as Potential In-Situ Treatments for the Contaminated Paducah Groundwater

    SciTech Connect

    Lewis, S; Li, Y; Xu, J; Tee, Y; Lynch, Andrew

    2007-05-01

    When considering reductive technologies for ground water remediation, it is important to understand the underlying principles that govern kinetics of zero-valent metal dechlorination. Studies involving the use of nanoscale metals (characteristic length <100nm) for chloro-organic degradation have increased reaction rates by 1-2 orders of magnitude with minimal intermediate formation. Typically, these metals are synthesized using modifications of the aqueous phase reduction of metal ions using sodium borohydride presented by Glavee and coworkers. The use of a bimetallic system increases the reactivity of the particle surface by incorporating a second metal that can typically act as a hydrogenation promotor.

  18. Alkaline-Earth-Catalyzed Dehydrocoupling of Amines and Boranes

    PubMed Central

    Liptrot, David J; Hill, Michael S; Mahon, Mary F; Wilson, Andrew S S

    2015-01-01

    Dehydrocoupling reactions between the boranes HBpin and 9-borabicyclo[3.3.1]nonane and a range of amines and anilines ensue under very mild reaction conditions in the presence of a simple β-diketiminato magnesium n-butyl precatalyst. The facility of the reactions is suggested to be a function of the Lewis acidity of the borane substrate, and is dictated by resultant pre-equilibria between, and the relative stability of, magnesium hydride and borohydride intermediates during the course of the catalysis. PMID:26360523

  19. Green coconut ( Cocos nucifera Linn) shell extract mediated size controlled green synthesis of polyshaped gold nanoparticles and its application in catalysis

    NASA Astrophysics Data System (ADS)

    Paul, Koushik; Bag, Braja Gopal; Samanta, Kousik

    2014-08-01

    The shell extract of green coconut ( Cocos nucifera Linn) has been utilized for the synthesis of gold nanoparticles at room temperature under very mild condition without any extra stabilizing or capping agents. The size of the synthesized gold nanoparticles could be controlled by varying the concentration of the shell extract. The stabilized gold nanoparticles were analyzed by surface plasmon resonance spectroscopy, HRTEM, Energy dispersive X-ray spectroscopy and X-ray diffraction studies. The catalytic activity of the freshly synthesized gold nanoparticles was studied for the sodium borohydride reduction of 4-nitrophenol and the kinetics of the reduction reaction were studied spectrophotometrically.

  20. Concentration of trace elements in water samples by reductive precipitation

    SciTech Connect

    Skogerboe, R.K.; Hanagan, W.A.; Taylor, H.E.

    1985-12-01

    The use of borohydride reduction as a means of preconcentrating elements by precipitation as the element or as a boride has been explored. It has been shown that the optimized procedure reproducibly effects the precipitation of all 18 elements studied; only four of these exhibited recoveries less than 90%. The general ease of use, the demonstrated accuracy and precision, the high preconcentration factors available, the self-cleansing properties of the primary reagent, the granular character of the precipitate are all factors to recommend this approach. 25 references, 1 figure, 4 tables.

  1. Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers

    PubMed Central

    2013-01-01

    In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride. PMID:23680063

  2. Labelling of membrane glycoprotein in erythrocytes infected with Plasmodium knowlesi*

    PubMed Central

    Trigg, P. I.; Hirst, S. I.; Shakespeare, P. G.; Tappenden, L.

    1977-01-01

    Normal rhesus monkey erythrocytes and erythrocytes infected by P. knowlesi were labelled with galactose oxidase (EC 1.1.3.9) and tritiated sodium borohydride. The glycoproteins of normal erythrocytes were not labelled unless the cells were pretreated with neuraminidase, when peaks of activity with apparent molecular weights of 170 000, 126 000, 90 000, 50 000, and 35 000 were observed. Schizont-infected erythrocytes showed an absence of glycoprotein labelling even after neuraminidase treatment. The results indicate that there is an alteration in the glycoproteins of schizont-infected erythrocytes, which may contribute to the increased permeability and the immunological alterations on the surface of these cells. PMID:412601

  3. π aromaticity and three-dimensional aromaticity: two sides of the same coin?

    PubMed

    Poater, Jordi; Solà, Miquel; Viñas, Clara; Teixidor, Francesc

    2014-11-01

    A bridge between classical organic polycyclic aromatic hydrocarbons (PAH) and closo borohydride clusters is established by showing that they share a common origin regulated by the number of valence electrons in an electronic confined space. Application of the proposed electronic confined space analogy (ECSA) method to archetypal PAHs leads to the conclusion that the 4n+2 Wade-Mingos rule for three-dimensional closo boranes is equivalent to the (4n+2)π Hückel rule for two-dimensional PAHs. More importantly, use of ECSA allows design of new interesting fused closo boranes which can be a source of inspiration for synthetic chemists. PMID:25223923

  4. Scalable synthesis of Cu-based ultrathin nanowire networks and their electrocatalytic properties.

    PubMed

    Hong, Wei; Wang, Jin; Wang, Erkang

    2016-02-25

    In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction. PMID:26880228

  5. Effect of fuel density and heating value on ram-jet airplane range

    NASA Technical Reports Server (NTRS)

    Henneberry, Hugh M

    1952-01-01

    An analytical investigation of the effects of fuel density and heating value on the cruising range of a ram-jet airplane was made. Results indicate that with present-day knowledge of chemical fuels, neither very high nor very low fuel densities have any advantages for long-range flight. Of the fuels investigated, the borohydrides and metallic boron have the greatest range potential. Aluminum and aluminum hydrocarbon slurries were inferior to pure hydrocarbon fuel and boron-hydrocarbon slurries were superior on a range basis. It was concluded that the practical difficulties associated with the use of liquid hydrogen fuel cannot be justified on a range basis.

  6. Synthesis of a sucrose dimer with enone tether; a study on its functionalization

    PubMed Central

    Pakulski, Zbigniew; Gajda, Norbert; Jawiczuk, Magdalena; Frelek, Jadwiga; Cmoch, Piotr

    2014-01-01

    Summary The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD) spectroscopy using the in situ dimolybdenum methodology. PMID:24991275

  7. Microbial oxidation of amines. Spectral and kinetic properties of the primary amine dehydrogenase of Pseudomonas AM 1

    PubMed Central

    Eady, R. R.; Large, P. J.

    1971-01-01

    1. An improved procedure is reported for purification of the amine dehydrogenase from methylamine-grown Pseudomonas AM1 which yielded a product homogeneous by sedimentation and disc-electrophoretic analysis, with molecular weight of 133000. 2. The purified enzyme had absorption maxima at 280 and 430nm. On aging, a third peak appeared at 325nm, and the 430nm peak decreased in intensity. This spectrum was independent of pH. 3. Addition of 2.5mm-semicarbazide, phenylhydrazine, hydrazine or hydroxylamine produced modified spectra with maxima respectively at 400, 440, 395 and 425nm. 4. Aerobic addition of methylamine resulted in a bleaching of the 430nm peak and the appearance of a new one at 325nm. This spectral change was retained after removal of the methylamine by dialysis. The original spectrum could be restored on addition of phenazine methosulphate. 5. Addition of borohydride partially inactivated the enzyme and produced spectral changes similar to those observed with methylamine. Pre-treatment with methylamine prevented the inactivation by borohydride. The degree of inactivation could be increased by alternate phenazine methosulphate and borohydride treatments. 6. The addition of methylamine or borohydride each caused shifts in the fluorescence emission maximum from 348 to 380nm. 7. Lineweaver–Burk plots of reciprocal activity against reciprocal concentration of either of the substrates n-butylamine or phenazine methosulphate were consistent with a mechanism that involves interconversion of two free forms of the enzyme by the two substrates. 8. The enzyme, although spectrally modified, was not inactivated by dialysis against diethyldithiocarbamate, and contained about 0.27 g-atom of copper/mol, with small traces of cobalt, iron and zinc. 9. Conventional methods of resolution did not release the prosthetic group. Heat denaturation after treatment of the enzyme with methylamine liberated a yellow chromophore which did not reactivate resolved aspartate

  8. Colloidal nickel boride catalyst for hydrogenation of olefins

    SciTech Connect

    Nakao, Y.; Fujishige, S.

    1981-04-01

    Colloidal nickel boride was prepared from nickel(II) chloride by reduction with sodium borohydride in the presence of polyvinylpyrrolidone in ethanol. Hydrogenation of various olefins was examined over the colloidal catalyst at 30/sup 0/C and atmospheric pressure. The colloidal nickel boride was much more effective than the precipitated nickel boride prepared in the absence of polyvinylpyrrolidone as a hydrogenation catalyst, especially for isopropenyl compounds. Additional amines and sodium acetate were slightly inhibitive to the colloidal catalyst, while, being strongly promotive to the precipitated catalyst. The colloidal nickel boride was superior to the charcoal-supported metals of the platinum group in catalytic activity for ..cap alpha..-methylstyrene.

  9. Synthesis of (/sup 75/Se)trimethylselenonium iodide from (/sup 75/Se)selenocystine

    SciTech Connect

    Foster, S.J.; Ganther, H.E.

    1984-02-15

    The synthesis of (/sup 75/Se)trimethylselenonium iodide from (/sup 75/)selenocystine is described. The starting compound is reduced to (/sup 75/Se)selenocysteine with borohydride and reacted with methyl iodide to form (/sup 75/Se)Se-methyl-selenocysteine, then treated with methyl iodide in formic acid solution to form Se-dimethyl-selenocysteine selenonium iodide. Over a period of days, the selenonium intermediate undergoes spontaneous elimination to form alanine and dimethyl selenide, which reacts with methyl iodide to give the trimethylselenonium product in over 90% yield. 15 references.

  10. Caffeic acid: potential applications in nanotechnology as a green reducing agent for sustainable synthesis of gold nanoparticles.

    PubMed

    Seo, Yu Seon; Cha, Song-Hyun; Yoon, Hye-Ran; Kang, Young-Hwa; Park, Youmie

    2015-04-01

    The sustainable synthesis of gold nanoparticles from gold ions was conducted with caffeic acid as a green reducing agent. The formation of gold nanoparticles was confirmed by spectroscopic and microscopic methods. Spherical nanoparticles with an average diameter of 29.99 ± 7.43 nm were observed in high- resolution transmission electron microscopy and atomic force microscopy images. The newly prepared gold nanoparticles exhibited catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. This system enables the preparation of green catalysts using plant natural products as reducing agents, which fulfills the growing need for sustainability initiatives. PMID:25973494

  11. Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers

    NASA Astrophysics Data System (ADS)

    Domènech, Berta; Ziegler, Kharla K.; Carrillo, Fernando; Muñoz, Maria; Muraviev, Dimitri N.; Macanás, Jorge

    2013-05-01

    In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride.

  12. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    NASA Astrophysics Data System (ADS)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  13. Comparative biodistribution studies of technetium-99 m radiolabeled amphiphilic nanoparticles using three different reducing agents during the labeling procedure.

    PubMed

    Geskovski, Nikola; Kuzmanovska, Sonja; Simonoska Crcarevska, Maja; Calis, Sema; Dimchevska, Simona; Petrusevska, Marija; Zdravkovski, Pance; Goracinova, Katerina

    2013-12-01

    Considering the confusing biodistribution data through the literature and few reported alerts as well as our preliminary biodistribution results, we decided to evaluate the interaction and interference of the commonly present (99m) Tc (technetium-99m)-stannic oxide colloid during the direct stannous chloride (99m) Tc-labeling procedure and to assess its influence on the biodistribution pattern of amphiphilic poly(lactic-co-glycolic acid) nanoparticles. In order to confirm our thesis, beside stannous chloride, we employed two different reducing agents that don't form colloidal particles. The use of sodium borohydride was previously reported in the literature, whereas sodium dithionite was adapted for the first time in the (99m) Tc direct labeling procedure for nanoparticles. The results in our paper clearly differentiate among samples with and without colloidal impurities originating from the labeling procedure with a logical follow up of the radiochemical, physicochemical evaluation, and biodistribution studies clarifying previously reported data on stannic oxide colloidal interference. (99m) Tc-nanoparticle complex labeled with sodium dithionite as reducing agent illustrated appropriate labeling efficacy, stability, and potential for further use in biodistribution studies thus providing solution for the problem of low-complex stability when sodium borohydride is used and colloidal stannic oxide interference for stannous chloride procedure. PMID:24339006

  14. Probing the structure, stability and hydrogen storage properties of calcium dodecahydro- closo-dodecaborate

    NASA Astrophysics Data System (ADS)

    Stavila, Vitalie; Her, Jae-Hyuk; Zhou, Wei; Hwang, Son-Jong; Kim, Chul; Ottley, Leigh Anna M.; Udovic, Terrence J.

    2010-05-01

    Calcium borohydride can reversibly store up to 9.6 wt% hydrogen; however, the material displays poor cyclability, generally associated with the formation of stable intermediate species. In an effort to understand the role of such intermediates on the hydrogen storage properties of Ca(BH 4) 2, calcium dodecahydro- closo-dodecaborate was isolated and characterized by diffraction and spectroscopic techniques. The crystal structure of CaB 12H 12 was determined from powder XRD data and confirmed by DFT and neutron vibrational spectroscopy studies. Attempts to dehydrogenate/hydrogenate mixtures of CaB 12H 12 and CaH 2 were made under conditions known to favor partial reversibility in calcium borohydride. However, up to 670 K no notable formation of Ca(BH 4) 2 (during hydrogenation) or CaB 6 (during dehydrogenation) occurred. It was demonstrated that the stability of CaB 12H 12 can be significantly altered using CaH 2 as a destabilizing agent to favor the hydrogen release.

  15. A multifaceted approach to hydrogen storage.

    PubMed

    Churchard, Andrew J; Banach, Ewa; Borgschulte, Andreas; Caputo, Riccarda; Chen, Jian-Cheng; Clary, David; Fijalkowski, Karol J; Geerlings, Hans; Genova, Radostina V; Grochala, Wojciech; Jaroń, Tomasz; Juanes-Marcos, Juan Carlos; Kasemo, Bengt; Kroes, Geert-Jan; Ljubić, Ivan; Naujoks, Nicola; Nørskov, Jens K; Olsen, Roar A; Pendolino, Flavio; Remhof, Arndt; Románszki, Loránd; Tekin, Adem; Vegge, Tejs; Zäch, Michael; Züttel, Andreas

    2011-10-14

    The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides. PMID:21887432

  16. Aqueous – Phase Synthesis of PAA in PVDF Membrane Pores for Nanoparticle Synthesis and Dichlorobiphenyl Degradation

    PubMed Central

    Smuleac, V.; Bachas, L.; Bhattacharyya, D.

    2009-01-01

    This paper deals with bimetallic (Fe/Pd) nanoparticle synthesis inside the membrane pores and application for catalytic dechlorination of toxic organic compounds form aqueous streams. Membranes have been used as platforms for nanoparticle synthesis in order to reduce the agglomeration, encountered in solution phase synthesis which leads to a dramatic loss of reactivity. The membrane support, polyvinylidene fluoride (PVDF) was modified by in situ polymerization of acrylic acid in aqueous phase. Subsequent steps included ion exchange with Fe2+, reduction to Fe0 with sodium borohydride and Pd deposition. Various techniques, such as STEM, EDX, FTIR and permeability measurements, were used for membrane characterization and showed that bimetallic (Fe/Pd) nanoparticles with an average size of 20-30 nm have been incorporated inside of the PAA-coated membrane pores. The Fe/Pd–modified membranes showed a high reactivity toward a model compound, 2, 2′-dichlorobyphenyl and a strong dependence of degradation on Pd (hydrogenation catalyst) content. The use of convective flow substantially reduces the degradation time: 43% conversion of dichlorobiphenyl to biphenyl can be achieved in less than 40 s residence time. Another important aspect is the ability to regenerate and reuse the Fe/Pd bimetallic systems by washing with a solution of sodium borohydride, because the iron becomes inactivated (corroded) as the dechlorination reaction proceeds. PMID:20161475

  17. FUNDAMENTAL ENVIRONMENTAL REACTIVITY TESTING AND ANALYSIS OF THE HYDROGEN STORAGE MATERIAL 2LIBH4 MGH2

    SciTech Connect

    James, C.; Anton, D.; Cortes-Concepcion, J.; Brinkman, K.; Gray, J.

    2012-01-10

    While the storage of hydrogen for portable and stationary applications is regarded as critical in bringing PEM fuel cells to commercial acceptance, little is known of the environmental exposure risks posed in utilizing condensed phase chemical storage options as in complex hydrides. It is thus important to understand the effect of environmental exposure of metal hydrides in the case of accident scenarios. Simulated tests were performed following the United Nations standards to test for flammability and water reactivity in air for a destabilized lithium borohydride and magnesium hydride system in a 2 to 1 molar ratio respectively. It was determined that the mixture acted similarly to the parent, lithium borohydride, but at slower rate of reaction seen in magnesium hydride. To quantify environmental exposure kinetics, isothermal calorimetry was utilized to measure the enthalpy of reaction as a function of exposure time to dry and humid air, and liquid water. The reaction with liquid water was found to increase the heat flow significantly during exposure compared to exposure in dry or humid air environments. Calorimetric results showed the maximum normalized heat flow the fully charged material was 6 mW/mg under liquid phase hydrolysis; and 14 mW/mg for the fully discharged material also occurring under liquid phase hydrolysis conditions.

  18. Comparison of palladium/zinc oxide photocatalysts prepared by different palladium doping methods for congo red degradation.

    PubMed

    Güy, Nuray; Çakar, Soner; Özacar, Mahmut

    2016-03-15

    ZnO nanoplates were synthesized by microwave-hydrothermal methods. Pd doped ZnO photocatalysts were prepared by microwave irradiation, UV irradiation, and borohydride reduction methods. The Pd/ZnO photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and UV-vis spectrophotometry. The obtained FESEM results confirmed the dispersion of Pd nanoparticles on the surface of ZnO nanoplates. The optical band gap value was calculated as 3.25 eV from UV-Vis diffuse reflectance spectra of ZnO and different Pd/ZnO photocatalysts. Since the preparation method of the photocatalyst is of great importance for determining the photocatalysis, the effect of this on photocatalysis was investigated. The results of the photocatalytic degradation of congo red in aqueous solutions under the UV-light showed that Pd/ZnO prepared by borohydride reduction method exhibited higher photocatalytic activity than the other ones. A plausible mechanism for the enhanced photocatalytic activity by Pd doped ZnO was proposed. The kinetics of photodecomposition of congo red, and the identification of photoproducts were investigated by using liquid chromatography-mass spectrometry (LC-MS). The possible photodegradation pathway of congo red was also proposed according to the structures of the photoproducts obtained from LC-MS data. PMID:26720515

  19. Surface geometry of tryptophan adsorbed on gold colloidal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hussain, Shafqat; Pang, Yoonsoo

    2015-09-01

    Two distinct surface-enhanced Raman (SER) spectra of tryptophan depending on the surface adsorption geometry were obtained by using colloidal gold nanoparticles reduced by borohydride and citrate ions. According to the vibrational assignments based on DFT simulations, the SER spectra of tryptamine and 3-indolepropionic acid, and the pH dependence of tryptophan SER spectrum, we found that some indole ring vibrations are very sensitive to the surface adsorption geometry of the molecules. With citrate-reduced gold colloids, tryptophan and related molecules mainly adsorb via the protonated amine group while maintaining a perpendicular geometry of the indole ring to the surface. However, a flat geometry of the indole ring to the surface is preferred on the borohydride-reduced gold colloids where the surface adsorption occurs mainly through the indole ring π electrons. By comparing our results with previous reports on the SER spectra of tryptophan on various silver and gold surfaces, we propose a general adsorption model of tryptophan on metal nanosurfaces.

  20. Study on Hydrogen Storage Materials

    NASA Astrophysics Data System (ADS)

    Sugiyama, Jun

    2016-09-01

    Complex hydrides have been heavily investigated as a hydrogen storage material, particularly for future vehicular applications. The present major problem of such complex hydrides is their relatively high hydrogen desorption temperature (Td). In order to find a predominant parameter for determining Td, we have investigated internal nuclear magnetic fields in several complex hydrides, such as, lithium and sodium alanates, borohydrides, and magnesium hydrides, with a muon spin rotation and relaxation (μ+SR) technique. At low temperatures, the μ+SR spectrum obtained in a zero external field (ZF) exhibits a clear oscillation due to the formation of a three spin 1/2 system, HμH, besides Mg(BH4)2 and Sc(BH4)2. Such oscillatory signal becomes weaker and weaker with increasing temperature, and finally disappears above around room temperature. However, the volume fraction of the HμH signal to the whole asymmetry at 5 K is found to be a good indicator for Td in borohydrides. At high temperatures, on the contrary, the ZF-spectrum for MgH2 shows a Kubo-Toyabe like relaxation due to a random nuclear magnetic field of 1H. Such nuclear magnetic field becomes dynamic well below Td in the milled MgH2, indicating a significant role on H-diffusion in solids for determining Td.

  1. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    PubMed Central

    2014-01-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested. PMID:25258607

  2. Scalable synthesis of Cu-based ultrathin nanowire networks and their electrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Hong, Wei; Wang, Jin; Wang, Erkang

    2016-02-01

    In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction.In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction. Electronic supplementary information (ESI) available: Experimental details, additional TEM, XPS and electrochemical characterizations. See DOI: 10.1039/c5nr07516e

  3. A non-reducing terminal fragment from tracheal cartilage keratan sulphate chains contains alpha (2-3)-linked N-acetylneuraminic acid.

    PubMed Central

    Dickenson, J M; Huckerby, T N; Nieduszynski, I A

    1991-01-01

    Keratan sulphate chains were isolated from bovine tracheal ring cartilage (15-18-month-old animals) after papain digestion of the tissue followed by ethanol fractionation, chondroitinase ABC digestion and alkaline borohydride reduction. The keratan sulphate chains were further purified by anion-exchange chromatography on a Pharmacia Mono-Q column in order to remove any contaminating chondroitin sulphate and O-linked oligosaccharides. The chains were then treated with keratanase and the digest was subjected to alkaline borohydride reduction, producing oligosaccharides with galactitol at their reducing ends. The reduced digest was chromatographed on a Nucleosil 5 SB anion-exchange column and individual oligosaccharides were isolated. One of these, oligosaccharide (I), was shown by 500 MHz 1H-n.m.r. spectroscopy to have the following structure: NeuAc alpha 2-3Gal beta 1-4GlcNAc(6SO4) beta 1-3Gal-ol (I) The structure of this oligosaccharide shows that keratan sulphate chains from bovine tracheal ring cartilage may be terminated with N-acetylneuraminic acid linked alpha (2-3) to an unsulphated galactose. Keratan sulphate chains were also isolated from bovine femoral head cartilage (15-18-month-old animals) using an identical protocol, but with keratanase which was subsequently shown to have sialidase activity. This yielded oligosaccharide (II), the unsialyated version of (I): Gal beta 1-4GlcNAc(6SO4) beta 1-3Gal-ol (II). PMID:1910336

  4. Spectroscopic and structural characterization of reduced technetium species in acetate media

    SciTech Connect

    Mausolf, Edward; Poineau, Frederic; Droessler, Janelle; Czerwinski, Kenneth R.

    2011-11-17

    The reduction of ammonium pertechnetate by sodium borohydride in 0.1 M NaOH/glacial acetic acid has been studied. The reduction products (solids and solutions) have been characterized by UV-Visible spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray emission spectroscopy (SEM/EDS), and X-ray absorption fine structure (XAFS) spectroscopy. UV-Visible spectra of the solution, after reduction, exhibit bands at 350 and 500 nm that have been attributed to the formation of polymeric Tc(IV) species. SEM/EDS on the solid (X-ray amorphous) indicates the absence of metallic Tc and the presence of oxygen. EXAFS measurements further indicate that the precipitate exhibits a [Tc({mu}-O){sub 2}Tc] core structure. XANES is consistent with the formation of Tc(III) and/or Tc(IV). Results infer that reduction of aqueous Tc(VII) by borohydride in the presence of acetic acid does not produce metallic Tc, but a mixture of various oxidation states of Tc near Tc(III) and Tc(IV).

  5. Flow injection method for the determination of silver concentration in drinking water for spacecrafts.

    PubMed

    Bruzzoniti, Maria Concetta; Kobylinska, Dorota Korte; Franko, Mladen; Sarzanini, Corrado

    2010-04-14

    A flow injection method has been developed for determination of silver. The method is based on a reduction reaction with sodium borohydride which leads to the formation of a colloidal species which is monitored at a wavelength of 390 nm. The reaction variables flow rate, sodium borohydride concentration and pH, which affect sensitivity, were investigated and their effects were established using a two-levels, three-factor experimental design. Further optimization of manifold variables (reaction coil and injection volume) allowed us to determine silver in the range 0.050-5.0 mg L(-1) with a minimum detectable concentration of 0.050 mg L(-1). Silver is added, as biocide, to drinking water for spacecrafts. The chemical species of silver, present in this kind of sample, were characterized by a procedure based on the selective retention of Ag(+) onto a 2.2.2. cryptand based substrate followed by determination of the non-bound and bound (after elution) Ag(+) by the FIA method. The method optimized was applied to a drinking water sample provided for the launch with the Automated Transfer Vehicle (ATV) module Jule Verne to the International Space Station (March 9, 2008). PMID:20381692

  6. Enhanced photoproduction of hydrogen peroxide by humic substances in the presence of phenol electron donors.

    PubMed

    Zhang, Yi; Simon, Kelli A; Andrew, Andrea A; Del Vecchio, Rossana; Blough, Neil V

    2014-11-01

    Addition of a series of phenol electron donors to solutions of humic substances (HS) enhanced substantially the initial rates of hydrogen peroxide (H2O2) photoproduction (RH2O2), with enhancement factors (EF) ranging from a low of ∼3 for 2,4,6-trimethylphenol (TMP) to a high of ∼15 for 3,4-dimethoxyphenol (DMOP). The substantial inhibition of the enhanced RH2O2 following borohydride reduction of the HS, as well as the dependence of RH2O2 on phenol and dioxygen concentrations are consistent with a mechanism in which the phenols react with the triplet excited states of (aromatic) ketones within the HS to form initially a phenoxy and ketyl radical. The ketyl radical then reacts rapidly with dioxygen to regenerate the ketone and form superoxide (O2-), which subsequently dismutates to H2O2. However, as was previously noted for the photosensitized loss of TMP, the incomplete inhibition of the enhanced RH2O2 following borohydride reduction suggests that there may remain another pool of oxidizing triplets. The results demonstrate that H2O2 can be generated through an additional pathway in the presence of sufficiently high concentrations of appropriate electron donors through reaction with the excited triplet states of aromatic ketones and possibly of other species such as quinones. However, in some cases, the much lower ratio of H2O2 produced to phenol consumed suggests that secondary reactions could alter this ratio significantly. PMID:25288017

  7. Kinetic analysis and chemical modification studies of nicotinate phosphoribosyltransferase from yeast

    SciTech Connect

    Hess, S.L.

    1988-01-01

    Nicotinate phosphoribosyltransferase (NaPRTase) from Baker's yeast catalyzes the formation of nicotinate mononucleotide (NaMN) and pyrophosphate from phosphoribosyl {alpha}-1-pyrophosphate and nicotinate, concomitant with ATP hydrolysis. Using purified NaPRTase, initial velocity measurements were performed varying one substrate concentration at different fixed levels of the second substrate and maintaining the third substrate constant. Subsequently, an exchange of label was observed between ATP and ({sup 14}C)-ADP. This rate of exchange was inhibited by PRibPP and pyrophosphate. Incubations of NaPRTase with pyridoxal 5{prime}-phosphate followed by sodium borohydride reduction led to inactivation of the enzyme. Pyridoxal was a less effective inhibitor than pyridoxal 5{prime}-phosphate. The inactivation of the enzyme by pyridoxal 5{prime}-phosphate was reversible upon flow dialysis, whereas reduction of the enzyme-pyridoxal complex with sodium borohydride rendered the inhibition irreversible. The presence of ATP or PRibPP, with or with Mg{sup 2+}, provided protection against this inactivation, while a kinetic analysis revealed the inhibition to be competitive, and noncompetitive, respectively. One mole of ({sup 3}H)-pyridoxal phosphate was required to completely inactivate the enzyme, which was reduced in the presence of MgATP and MgPRibPP to 0.2 and 0.6, respectively. No incorporation of pyridoxal 5{prime}-phosphate was observed in the combination of both of the two substrates.

  8. Explorations of Novel Energy Conversion and Storage Systems

    NASA Astrophysics Data System (ADS)

    Duffin, Andrew Mark

    . As a result, liquid microjets yield conversion efficiencies exceeding 10%, much larger than channel-dependent measurements (˜3%). It is the large potentials obtainable with electrokinetic currents (tens of kilovolts) that drive up the electrical conversion efficiency. Unfortunately, low currents with high voltages are inconvenient for application. Section 3 of Chapter 2 describes efforts to utilize the high voltage of electrokinetic currents by coupling light into the process. More specifically, the streaming potential is used to modify the space charge layer in a semiconductor and, consequently, the light harvesting characteristics of that semiconductor. To this end, microchannel jets fabricated out of glass and silicon were built to allow light to impinge on the current generating surface. Although plagued with inconsistent results, streaming currents were found to increase upon illumination and some channels even gave measurable responses to ambient room lights. Chapter 3 of this dissertation addresses the details of hydration of boron-oxides and sodium borohydride as studied by near edge x-ray absorption fine structure spectroscopy (NEXAFS) and associated theory. Boron-oxides and molecular hydrogen are products of borohydride hydrolysis which has been intensely studied for hydrogen storage purposes. In spite of their hydroxide moieties, boron-oxides turn out to not be strongly hydrated by water. The experimental spectra, as well as attending calculations, show no evidence for electronic coupling that would indicate strong hydrogen bonding between the boron-oxides and water. On the other hand, the NEXAFS spectrum of sodium borohydride is significantly altered by water. The experiment and calculations show strong evidence for short dihydrogen bonds between water hydrogens and borohydride hydrogens. Molecular dynamics simulations indicate that borohydride is hydrated at the tetrahedral corners and edge.

  9. Study of Leishmania major-infected macrophages by use of lipophosphoglycan-specific monoclonal antibodies.

    PubMed

    Handman, E

    1990-07-01

    Leishmania major infection of macrophages is followed by a time-dependent appearance of lipophosphoglycan (LPG) that can be detected on the surface of infected cells by monoclonal antibodies. The origin of these LPG epitopes is probably the intracellular amastigote. LPG epitopes could be detected on the amastigote and the infected macrophage by a number of monoclonal antibodies directed to several distinct determinants on the phosphoglycan moiety. The macrophage-expressed LPG may be modified because, unlike the parasite LPG as expressed on promastigotes or amastigotes, it could not be radiolabeled by galactose oxidase or periodate treatment of infected cells followed by reduction with 3H-labeled sodium borohydride. Some LPG epitopes displayed on the macrophage may be anchored with glycosylphosphatidylinositol, and some may be in the water-soluble phosphoglycan form bound to macrophage integrins involved in its specific recognition. The water-soluble population could be released from the infected macrophage by gentle protease treatment. PMID:1694823

  10. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    PubMed

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. PMID:24433897