Transition Metal-Decorated Nanotubes and C 60; high-capacity hydrogen storage mediumIntroduction | Dissociative Absorption of H2 | Molecular Absorption | 4th top-H2 | The lowest energy isomer | Bonding Mechanism | Does Pt/Pd also work? | MD simulations | High concentration metal-coverages | Ti-decorated C60 | Conclusions
Dissociative Adsorption of a single H2 over Ti-SWNT
Figure shows the energy variation as a single H2 molecule approaches t80Ti. The energy first decreases slowly as the hydrogen gets closer to the nanotube and Ti. However, as the charge overlap gets large, the H2 molecule is attracted towards the Ti atom with a sudden decrease in the energy. At this point, the H2 molecule is still intact with a significantly increased H-H bond length of 0.86 Å. The second sudden decrease in energy is achieved by dissociating the H2 molecule into two H atoms. At this point, the H-H distance increases from 0.86 Å to 2.71 Å. The interaction between H2 and t80Ti is always attractive and therefore H2 is absorbed onto a Ti atom without any energy barrier. The energy gain through this dissociative adsorption is about 0.83 eV with respect to spin-polarized calculations for the isolated H2 and t80Ti systems.