CoO nanocrystals as a highly active catalyst for the generation of hydrogen from hydrolysis of sodium borohydride

We report the excellent catalytic performance of CoO nanocrystals on the catalytic hydrolysis of alkaline NaBH4 solutions. CoO nanocrystals with octahedral and near-spherical shapes are synthesized using a facile chemical solution method that employed cobalt acetate tetrahydrate as metal precursor in the presence of oleylamine. The octahedral CoO nanocrystals typically have a size of 40–50 nm, while the near-spherical nanocrystals have a size varying from 8 to 13 nm. Both of them have a face centered cubic (fcc) crystalline phase. Catalytic tests show that the as-synthesized CoO nanocrystals exhibit very high activities for the H2 generation from the hydrolysis of alkaline NaBH4 solutions. The maximum hydrogen generation rate of the as-synthesized CoO nanocrystals exceeds most reported values of transition metal or noble metal contained catalysts performed in alkaline NaBH4 solutions. The influences of shape on the catalytic behaviors of as-synthesized CoO nanocrystals are also compared and analyzed. The results presented in this study indicate that CoO nanocrystals are a promising candidate to replace noble metal catalysts in the H2 generation from the hydrolysis of borohydrides. [Display omitted] ▸ A new catalyst for the generation of H2 from hydrolysis of NaBH4 has been found. ▸ Octahedral and near-spherical CoO nanocrystals exhibit excellent catalytic property. ▸ A maximum H2 generation rate of 8333 ml min−1 g−1 has been obtained at 303 K. ▸ Exposed crystal facets make differences to the catalytic behavior. ▸ CoO nanocrystals can be a promising candidate for substituting noble metal catalyst.