Cobalt oxide supported multi wall carbon nanotube catalysts for hydrogen production via sodium borohydride hydrolysis

Abstract

Cobalt oxide supported multi-wall carbon nanotubes (Co/MWCNTs) catalysts with different cobalt oxide loadings were synthesized by simple impregnation method. The synthesized Co/MWCNTs materials were used as catalysts for hydrolysis of sodium borohydride (NaBH4), an effective route to produce clean hydrogen. The effect of some parameters such as Co loading, reaction temperature and reaction time were investigated on the performance of catalysts in hydrolysis of NaBH4. The hydrogen generation rate was found to be 409 mLg−1min−1 at 35 °C for Co/MWCNTs-20 catalyst in NaBH4 hydrolysis, while it is 28 mLg−1min−1 for bulk MWCNTs support. The physico-chemical characteristics such as crystalline phase, morphology, particle size, reducibility, surface and textural properties of the catalysts were studied by using powder XRD, FE-SEM, TEM, N2-physorption, XPS and H2-TPR techniques. The reduction temperature of cobalt oxide species was shifted to lower temperatures after impregnation of nanosized Co oxides on the MWCNTs support. It was also observed that presence of more number of surface Co2+ species in Co/MWCNTs-20 catalyst is responsible for superior activity in catalytic hydrolysis of NaBH4. The obtained results also suggested that Co/MWCNTs catalysts can be reused for five cycles with a slight loss of activity.