Metal-cluster (Be, Sc, Ti) decorated C24 nanocages and their hydrogen storage performance

Single Be, Sc, Ti metal atom and their cluster (dimer and trimer) decorated C₂₄ nanocages are considered for hydrogen storage. A comparison of single metal atom, dimer, and trimer decorated C₂₄ nanocages and their hydrogen storage performance is carried out. Decoration of single Be atom on C₂₄ nanocage distorts the nanocage and it is not suitable for hydrogen storage. Be₂, Be₃, Sc, Sc₂, Sc₃, Ti, Ti₂, and Ti₃ metal atom/cluster decoration do not distort the C₂₄ nanocage geometry before H₂ adsorption. After H₂ adsorption Sc₂, Sc₃ and Ti₃ clusters get broken into their constituent atoms and do not remain in cluster form. Among the metal cluster decorated C₂₄ structures considered, C₂₄Ti and C₂₄Ti₂ show thermodynamically favorable H₂ adsorption at ambient conditions without distorting the metal cluster after H₂ adsorption and thus they are more suitable for hydrogen storage at ambient conditions than the other structures considered. Though the Sc₃ and Ti₃ cluster decorated C₂₄ nanocages show the highest and second highest H₂ uptake capacity among all the structures considered and also thermodynamically favorable H₂ adsorption at ambient conditions, the Sc₃ and Ti₃ clusters get broken after maximum H₂ molecules adsorption.