Modified carbon nanotubes for hydrogen storage at moderate pressure and room temperature

In this study, the cup stacked carbon nanotubes (CSCNTs) co-modified by KOH activation and Ni decoration are used for hydrogen storage at room temperature and 2 MPa for the first time. The TEM and N-2 sorption analyses indicate that the micropore volume of CSCNTs can be improved over 12 times by KOH activation due to their unique graphene layer stacking structure, consequently, the hydrogen adsorption capacity of them increases nine times. Removing the amorphous carbon layers of CSCNTs by KOH etching is the precondition for successful Ni decoration. If the micropore volume of CSCNTs keeps unchanged, the hydrogen storage capacity of them can be further improved 85% by Ni decoration due to the spillover effect. However, during actual Ni decoration, the high micropore volume of CSCNTs obtained by KOH activation is reduced unavoidably because of the blocking effect of Ni nanoparticles, consequently, the resultant hydrogen adsorption capacity increases only 25%.