Nanocomposites and nanomaterials

Ni-, Co-spinel – carbon nanotubes composites: synthesis, structure and catalytic properties
A.S. Voronova, I.M. Ivanenko, Y.M. Romanenko 
National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute" 03056, Kyiv, pr. Pеremohy 37, building 4 anastasiavoronova666@gmail.com; irinaivanenko@hotmail.com

Portable hydrogen energy devices demand new H2 storage materials as efficient fuel sources with high energy density and low cost based upon pure H2 suppliers. Sodium borohydride is a nonflammable, non-toxic compound for such purposes. In theory, 4 mol of H2 can be produced from each mole of NaBH4 by utilizing H atoms in water. A suitable catalyst provides a high rate of H2 generation via hydrolysis of NaBH4 in a controllable reaction [1].
The cost and availability of catalyst in the process hydrogen generation from hydrolysis of NaBH4 with various catalysts are predominantly parameters. Unfortunately, there are many engineering problems, such as high cost, low catalyst durability caused by the solubility limitations of sodium by-products, borohydride and sodium metaborate (NaBO2) in an aqueous solution [2].
Mixed transition metal oxides with the spinel structure represent the most important group of materials with high catalytic activity. Ni-, Co-spinels are potentially useful because of their advantages such as high activity, cheapness, availability and satisfactory thermodynamic stability. The disadvantages of spinels as well as of other oxide compounds include low specific surface area. This disadvantage can be eliminated by applying a pure spinel to the surface of a porous matrix, which carbon nanotubes are.
A series of Ni-, Co-spinel – carbon nanotubes composites by copresipitation of Nickel and Cobalt nitrates synthesized. Morphology, particle size, phase and quantitative composition, lattice parameters, surface area and pore sizes distribution studied with SEM, TEM, XRD, IR, TG and BET methods. Catalytic activity in borohydride hydrolysis reaction at temperatures of 50 and 60 °C investigated. The dependence of the borohydride hydrolysis rate on the temperature and concentration of sodium hydroxide established.

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2.	Li H., Liao J., Zhang X., Liao W., Wen L., Yang J., Wang H., Wang R. Controlled synthesis of nanostructured Co film catalysts with high performance for hydrogen generation from sodium borohydride solution // J Power Sources.-2013.- 239.-P.277-283.