Monodisperse nickel nanoparticles supported on SiO 2 as an effective catalyst for the hydrolysis of ammonia-borane

Nano Research (Impact Factor: 7.01). 09/2010; 3(9):676-684. DOI: 10.1007/s12274-010-0031-7


Monodisperse Ni nanoparticles (NPs) have been synthesized by the reduction of nickel(II) acetylacetonate with the borane-tributylamine
complex in a mixture of oleylamine and oleic acid. These Ni NPs are an active catalyst for the hydrolysis of the ammonia-borane
(AB, H3N·BH3) complex under ambient conditions and their activities are dependent on the chemical nature of the oxide support that they
were deposited on. Among various oxides (SiO2, Al2O3, and CeO2) tested, SiO2 was found to enhance Ni NP catalytic activity due to the etching of the 3.2 nm Ni NPs giving Ni(II) ions and the subsequent
reduction of Ni(II) that led to the formation of 1.6 nm Ni NPs on the SiO2 surface. The kinetics of the hydrolysis of AB catalyzed by Ni/SiO2 was shown to be dependent on catalyst and substrate concentration as well as temperature. The Ni/SiO2 catalyst has a turnover frequency (TOF) of 13.2 mol H2·(mol Ni)−1 · min−1—the best ever reported for the hydrolysis of AB using a nickel catalyst, an activation energy of 34 kJ/mol ± 2 kJ/mol and
a total turnover number of 15,400 in the hydrolysis of AB. It is a promising candidate to replace noble metals for catalyzing
AB hydrolysis and for hydrogen generation under ambient conditions.

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Available from: Saim Özkar, Jun 06, 2014
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    • "ScienceDirect journal h ome page: te/he hydrides, Sodium Borohydride (NaBH 4 ) has gained much attention due to its environmentally benevolent nature, high Hydrogen content (10.8 wt%), easy availability and acceptable Hydrogen generation rate even at low temperature using low cost catalyst [6]. Schlesinger et al. [7] established that Hydrolysis of 1 atom of NaBH 4 produces 4 atoms of Hydrogen gas and watersoluble Sodium meta borate (NaBO 2 ), in the presence of appropriate catalyst according to the following stoichiometric equation: "
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    ABSTRACT: A highly active and stable bimetallic nano-hybrid catalyst Graphene-Cobalt-Platinum (G-Co-Pt) is proposed for the enhanced and cost effective generation of hydrogen from Sodium Borohydride. Three different nano-hybrid catalysts namely Graphene-Cobalt (G-Co), Graphene-Platinum (G-Pt) and Graphene-Cobalt-Platinum (G-Co-Pt) are synthesized, characterized using XRD, FTIR, SEM, HRTEM, EDAX and Cyclic voltammetry (CV) analysis and tested for hydrogen generation. The activity and stability of the catalysts are analyzed by estimating the turnover frequency (TOF), the electrochemically active surface area (ECSA), the percentage decay of current density over ten cycles of CV and the decay in the rate of hydrogen generation with the age of catalyst. Among the three catalysts G-Co-Pt exhibits the highest catalytic activity (TOF = 107 min(-1), ECSA = 75.32 m(2)/gm) and stability. The evaluated value of activation energy of the catalytic hydrolysis using G-Co-Pt is 16 +/- 2 kJ mol(-1). Copyright
    Full-text · Article · Jul 2014 · International Journal of Hydrogen Energy
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    • "In contrast, the amount of hydrogen evolution in the presence of hollow silicaenickel composite spheres is lower than both the ideal amount of hydrogen evolution estimated from reactions (2) and (3), indicating that the hollow silicaenickel composite spheres show no activity for hydrolysis of NH 3 BH 3 . On the other hand, the hydrogen production rate in the presence of titaniaenickel composite spheres is slightly lower than that in the presence of nickel-based composite spheres previously reported [18] [21] [25] [26] [28] [29], however, it is possible for the titaniae nickel composite spheres to improve the catalytic activity with controlling the particle size, the wall thickness, or the pore size in wall or hollow space. The as-prepared hollow metal oxideenickel composite spheres were characterized by using FTIR spectroscopic methods to confirm that the difference in the catalytic activity depends on the amount of residual PS templates. "
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    ABSTRACT: In this paper, we report an effective approach to the fabrication of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres. In this approach, metal oxide–nickel composite shells were coated on polystyrene particles by the sol–gel method and the polystyrene templates were dissolved subsequently, or even synchronously, in the same medium to form hollow spheres. Neither additional dissolution nor a calcination process was needed to remove the polystyrene templates. The as-prepared hollow metal oxide–nickel composite spheres were characterized by transmission electron microscopy. The catalytic activities of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres for hydrolytic dehydrogenation of aqueous NaBH4/NH3BH3 solution were compared. The evolutions of 64, 58, and 18 mL hydrogen were finished in about 49, 69, and 162 min in the presence of the hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres from aqueous NaBH4/NH3BH3 solution, respectively. The molar ratios of the hydrolytically generated hydrogen to the initial NH3BH3 both in the presence of hollow titania–nickel composite spheres, hollow zirconia–nickel composite spheres, and hollow silica–nickel composite spheres are 2.8, 2.4, and 0.1 (the theoretical value of 3.0), respectively, indicating that the hollow titania–nickel composite spheres and hollow zirconia–nickel composite spheres show much higher hydrogen evolution rates and the amount of hydrogen evolution via hydrolytic dehydrogenation of ammonia borane than the hollow silica–nickel composite spheres. From the results of ATR-IR spectra, a certain amount of residual PS templates exists in hollow silica–nickel composite spheres, and the amount of the residual PS templates were able to be reduced by increasing the amount of aqueous ammonia solution used for the preparation. The catalytic activity of hollow silica–nickel composite spheres increases when the amount of residual PS templates decreases.
    Full-text · Article · Feb 2013 · International Journal of Hydrogen Energy
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    ABSTRACT: Platinum clusters are prepared by γ radiolysis of beta zeolite suspensions (Pt-Beta) in the presence of a templating agent (tetraethylammonium hydroxide, TEAOH). Further, the Pt-Beta suspensions were stabilized with methyl cellulose and deposited in thin films with a thickness of 200 nm on silicon wafers. Elucidation of the size, distribution, and stability of the Pt clusters in the colloidal suspensions and thin films is provided by high-resolution transmission electron microscopy (HRTEM) combined with grazing incident X-ray diffraction (GI-XRD) measurements. The lateral length of the Pt clusters immobilized in the channels of the beta nanocrystals is between 1 and 2 nm. The presence of crystalline fringes with spacings of 0.23 and 1.26 nm corresponding to cubic Pt and zeolite beta are clearly seen in the HRTEM. The homogeneous distribution of the clusters along the film thickness is confirmed by GI-XRD measurements at two penetration depths. Besides, the location of the Pt clusters in the channels of beta nanoparticles is studied by FTIR spectroscopy. The Pt clusters confined in the channels of beta crystals decrease the total micropore volume and also lower the water sorption capacity in comparison with pure beta zeolite.
    No preview · Article · Nov 2010 · The Journal of Physical Chemistry C
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