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

A Co–B catalyst is used to generate hydrogen from alkaline aqueous NaBH 4 solutions. This study examined the properties of a Co–B catalyst prepared using different precursors ( CoCl 2 and CoSO 4 ) and NaBH 4 / Co 2 + mole ratios (0.67, 1.5, 3) at calcination temperatures of 130, 250 and 450 ∘ C . As the calcination temperature was increased in N 2 atmosphere mixed with 1% air, the typical amorphous structure of Co–B disappeared and the X-ray diffraction peaks corresponding to Co 3 O 4 became sharper. Metallic Co was formed when a NaBH 4 / Co 2 + mole ratio of 3 was used as the reductant with a corresponding reduction in the rate of H 2 generation. The highest level of H 2 generation (2400 ml/min g) was obtained with CoCl 2 as the precursor, a NaBH 4 / CO 2 + mole ratio of 1.5 as the reductant, and a calcination temperature of 250 ∘ C .