Hydrogen storage behavior of one-dimensional TiBx chains.

We designed a series of one-dimensional TiB(x) (x = 2-6) chains used for hydrogen storage. Among them, TiB(5) possesses the lowest heat of formation and the highest binding energy, and is the most energetically favorable configuration. The binding energy per atom in TiB(5) is even larger than that in a Ti dimer, which suggests the preference of Ti atoms to combine with B(5) clusters rather than clustering. Each Ti atom in the TiB(5) chain can host four hydrogen molecules (corresponding to a hydrogen storage capacity of 7.3 wt%) with an average binding energy of 43.7 kJ mol(-1)/H(2). The significant charge transfer and strong Kubas sigma-H(2) interaction between H(2) and Ti atoms contribute to the ideal dihydrogen binding energies.