Effect of preparation method on Co-B catalytic activity for hydrogen generation from alkali NaBH₄ solution

A Co-B catalyst is used to generate hydrogen from alkaline aqueous NaBH₄ solutions. This study examined the properties of a Co-B catalyst prepared using different precursors (CoCl₂ and CoSO₄) and NaBH₄ / Co^{2 +} mole ratios (0.67, 1.5, 3) at calcination temperatures of 130, 250 and 450 ^{{ring operator}} C. As the calcination temperature was increased in N₂ atmosphere mixed with 1% air, the typical amorphous structure of Co-B disappeared and the X-ray diffraction peaks corresponding to Co₃ O₄ became sharper. Metallic Co was formed when a NaBH₄ / Co^{2 +} mole ratio of 3 was used as the reductant with a corresponding reduction in the rate of H₂ generation. The highest level of H₂ generation (2400 ml/min g) was obtained with CoCl₂ as the precursor, a NaBH₄ / CO^{2 +} mole ratio of 1.5 as the reductant, and a calcination temperature of 250 ^{{ring operator}} C.