Multi-functionalized naphthalene complexes for hydrogen storage

A density functional study of hydrogen uptake capacity of multi-functionalized naphthalene with Ti and Li metal atom has been carried out. It is observed that, the naphthalene functionalized with two Ti atoms can interact with total eight hydrogen molecules in which each Ti metal atom interacts with four hydrogen molecules. Naphthalene decorated with two Li atoms can interact with total three H2 molecules only. First (19Li) and second (20Li) Li atom can interact with only one and two hydrogen molecule respectively. It is observed that, hydrogen molecules bind strongly to the C10H8Ti2 complex than C10H8Li2 complex. The gravimetric hydrogen uptake capacity of C10H8Ti2 and C10H8Li2 complex is found to be 6.72 and 3.73 wt% respectively. Moreover, after functionalizing naphthalene with four Li atoms, the uptake capacity is increased to 7.20 wt %. However, the thermochemistry result favors to Ti functionalized naphthalene complex (C10H8Ti2) for hydrogen storage over Li functionalized naphthalene (both C10H8Li2 and C10H8Li4) complexes. Atom-centered density matrix propagation (ADMP) molecular dynamics simulations have been performed which showed that C10H8Li2 and C10H8Li4 complex cannot bind single hydrogen molecule at room temperature whereas C10H8Ti2 can bind five hydrogen molecules.

► The gravimetric H2 uptake capacity of C10H8Ti2 complex is 6.72 wt%.
► Uptake capacity of C10H8Li2 and C10H8Li4 complex is 3.73 and 7.20 wt% respectively.
► C10H8Ti is more promising material for hydrogen adsorption.
► C10H8Ti2 can bind five hydrogen molecules as shown by ADMP-MD results.