H+ ions on graphene electrode as hydrogen storage reservoirs

A new idea for hydrogen storage is proposed in which H+ ions are adsorbed chemically on graphene sheet and it is possible to overcome the fundamental problem of current methods that hydrogen is not able to reversibly adsorbed/desorbed in appropriate temperature and under moderate pressure. As the top priority to test the feasibility, H+ ions storing capacity is studied by theoretical calculations. And the bonding and structural properties of H+/graphene complexes are investigated thoroughly. Our data yield promising results. The graphene fragment C62H20, in a quasi one-dimensional arch-like tunnel geometry, can absorb up to 54 H+ ions on the same side (6.6 wt.% H2) while maintaining its conductivity because of the sp2-rich structure. The feasibility of the new idea is proved from a viewpoint of hydrogen storing capacity. Additional calculation using an infinite graphene sheet model gives credibility to our conclusions. Considering the successful development of synthesis techniques in mass-producing atom-thick graphene sheets, it is really worth expecting a hydrogen-based energy economy can be realized by hydrogen-ion storage graphene electrodes.

► The bonding and structural properties of H+/graphene complexes are theoretically investigated. ► The graphene fragment C62H20, in a arch-like tunnel geometry, can bind chemically up to 6.6 wt.% H+ ions. ► The distorted C62H20 is still sp2-rich, which guarantees the distorted graphene still qualified as an electrode. ► Additional calculation using an infinite graphene sheet model adds further credibility to our numerical results.