Catalytic activities of non-noble metals for hydrogen generation from aqueous ammonia-borane at room temperature

We have studied catalytic performance of supported non-noble metals for hydrogen generation from aqueous NH3BH3 at room temperature. Among the tested non-noble metals, supported Co, Ni and Cu are the most catalytically active, with which hydrogen is released with an almost stoichiometric amount from aqueous NH3BH3, whereas supported Fe is catalytically inactive for this reaction. Support effects on the catalytic activity have been investigated by testing the hydrogen generation reaction in the presence of Co supported on gamma-Al2O3, SiO2 and C and it is found that the Co/C catalyst has higher activity. Activation energy for hydrogen generation from aqueous NH3BH3 in the presence of Co/gamma-Al2O3 was measured to be 62 kJ mol(-1); this may correspond to the step of B-N bond breaking. Particle size, surface morphology and surface area of the supported metal catalysts were examined by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) and BET experiments. It is found that with decreasing the particle size the activity of the supported catalyst is increased. The low-cost and high-performance supported non-noble metal catalysts may have high potential to find its application to the hydrogen generation for portable fuel cells. (c) 2006 Elsevier B.V. All rights reserved.