Hydrogen adsorption and storage on Ni-decorated CNC has been investigated by using DFT. A single
Ni atom decorated CNC adsorbs up to six H2 with a binding energy of 0.316 eV/H2. The interaction
of 3H2 with Ni-CNC is irreversible at 603 K. In contrast, the interaction of 4H2 with Ni-CNC is
reversible at 456 K. Further characterizations of the two reactions are considered in terms of the
projected densities of states, electrophilicity, and statistical thermodynamic stability. The free
energy of the reaction between 4H2 and Ni-CNC, surface coverage and rate constants ratio meet the
ultimate targets of DOE at 11.843 atm, 0.925 and 1.041 respectively. The Ni-CNC complexes can
serve as high-capacity hydrogen storage materials with capacities of up to 11.323 wt.%. It is illustrated
that unless the access of oxygen to the surface is restricted, its strong bond to the decorated
systems will preclude any practical use for hydrogen storage. |
