The hydrogen storage properties of the Ti decorated benzene-Ti-graphene sandwich-type structures

Abstract

The density functional theory is used to study the hydrogen storage properties of the transition metal Ti decorated benzene-Ti-graphene(BTG) sandwich-type structures. The calculated binding energy (8.27 and 8.62eV) of the Ti atom to the hollow site of the zigzag and armchair substrate in the BTG sandwich-type structures are nearly double of the corresponding cohesive energy of metal Ti(4.85 eV/atom) and the binding energy of the Ti atom above the hollow site of the graphitic sheet(4.74 eV), consequently allowing the atomic dispersion of Ti atoms without clustering. Therefore, the adsorption of H2 molecules between by the Ti atoms in the sandwich-type structures will be experimentally feasible. The calculated average adsorption energies of molecular hydrogen around Ti in the sandwich-type structures are in the range of 0.27–0.41 eV, which intermediates between physisorbed and chemisorbed states(0.1–0.8 eV). The maximum H2 molecules adsorbed by each Ti in the BTG structure should be 2. The partial density of states and the difference charge densities explore that the Ti sites adsorb molecular hydrogen mainly through the well-known Dewar–Kubas interaction. The calculated desorption temperature and molecular dynamic simulation indicate that the sandwich-type hydrogenated structures are easier to desorb H2 molecules. Therefore, the Ti decorated BTG sandwich-type structures are appropriate for hydrogen storage at near-ambient conditions.