C2H2M (M = Ti,Li) complex: A possible hydrogen storage material

The hydrogen storage capacity of Ti-acetylene (C₂H₂Ti) and Li-acetylene (C₂H₂Li) complex has been tested using second order Møller Plesset method with different basis sets. Single Ti(Li) decorated acetylene complex can adsorb maximum of five(four) hydrogen molecules, which corresponds to the gravimetric hydrogen storage capacity of 12(19.65) wt % and it meets the target of 9 wt % by 2015 specified by US Department of Energy. The hydrogen adsorption energies with zero point energy and Gibbs free energy correction show that hydrogen adsorption on C₂H₂Ti is energetically favourable for a wide range of temperature and that is unfavourable on C₂H₂Li complex even at a very low temperature. Atom centered density matrix propagation molecular dynamics simulations reveal that four H₂ molecules remain adsorbed on C₂H₂Ti complex at 300 K. Though H₂ uptake capacity of C₂H₂Li complex is higher than that of C₂H₂Ti complex, the thermochemistry results favour to C₂H₂Ti complex over C₂H₂Li complex as a possible hydrogen storage media.