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

Nano Research (Impact Factor: 7.39). 01/2010; 3(9):676-684. DOI: 10.1007/s12274-010-0031-7

ABSTRACT 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.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cobalt(0) nanoclusters embedded in silica (Co@SiO2) were prepared by a facile two-step procedure. In the first step, the hydrogenphosphate anion (HPO42−) stabilized cobalt(0) nanoclusters were in situ generated from the reduction of cobalt(II) chloride during the hydrolysis of sodium borohydride (NaBH4) in the presence of stabilizer. Next, HPO42− anion-stabilized cobalt(0) nanoclusters were embedded in silica formed by in situ hydrolysis and condensation of tetraethylorthosilicate added as ethanol solution. Co@SiO2 can be separated from the solution by vacuum filtration and characterized by UV–Vis electronic absorption spectroscopy, TEM, SEM-EDX, ATR-IR and ICP-OES techniques. Co@SiO2 are found to be highly active and stable catalysts in the hydrolysis of ammonia borane (AB) even at low cobalt concentration and room temperature. They provide an initial turnover frequency of 13.3 min−1 and 24,400 total turnovers over 52 h in the hydrolysis of AB at 25.0 ± 0.5 °C. Moreover, Co@SiO2 retain 72% and 74% of the initial activity after ten runs recyclability and five cycles reusability test in the hydrolysis of AB, respectively. The kinetics of hydrogen generation from the hydrolysis of AB catalyzed by Co@SiO2 was studied depending on the catalyst concentration, substrate concentration, and temperature. The activation parameters of this catalytic reaction were also determined from the evaluation of the kinetic data.
    Fuel and Energy Abstracts 01/2011; 36(18):11528-11535.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tris(bipyridine)nickel(II) chloride (1) and bis(bipyridine)nickel(II) chloride (2) pyrolize at heating rate of 50 °C/min to a maximum of 450 °C for 24 h under an inert atmosphere of flowing argon gas, to yield size-controlled nickel nanoparticles. Thermogravimetric studies of the complexes (1) and (2) and GC–MS analysis of the trapped volatile matter evolved during thermal degradation of the complexes indicate their clean decomposition pathway to zero-valent nickel. Both heating rate and argon gas flow rate affect purity, particle size, and shape of the particles. X-ray powder diffractometry and atomic force microscopy showed the formation of face-centered cubic (fcc) structured nickel particles having particle size in the range of 3.5–5.0 nm. Magnetic susceptibility measurements suggest nickel nanoparticles to be ferromagnetic in nature characterized by particle size–dependent Curie temperature and high coercivity that is comparable to the bulk iron.
    Journal of Thermal Analysis and Calorimetry 12/2011; 111(1). · 1.98 Impact Factor
  • Source
    International Journal of Hydrogen Energy 07/2014; 39(22):11566–11577. · 3.55 Impact Factor


Available from
Jun 6, 2014