High Capacity Hydrogen Storage in Ni Decorated Carbon Nanocone: A First-Principles Study

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.