| Summary: | A solid-state NaBH<sub>4</sub>/Co composite has been employed as a hydrogen-generating material, as an alternative to sodium borohydride solutions, in the long storage of hydrogen. Hydrogen generation begins in the presence of cobalt-based catalysts, immediately after water is added to a NaBH<sub>4</sub>/Co composite, as a result of sodium borohydride hydrolysis. The hydrogen generation rate has been investigated as a function of the pressure used to press hydrogen-generating composites from a mechanical mixture of the hydride and cobalt chloride hexahydrate. The hydrogen generation rate was observed to increase with the increase of this pressure. Pre-reduction of the cobalt chloride, using a sodium borohydride solution, leveled this dependence with a two-fold decrease in the gas generation rate. According to TEM and XPS data, oxidation of the particles of the pre-reduced cobalt catalyst took place during preparation of the composites, and it is this oxidation that appears to be the main reason for its low activity in sodium borohydride hydrolysis.
|
|---|