Mechanism for high hydrogen storage capacity on metal-coated carbon nanotubes: A first principle analysis

► Each transition metal atom can adsorb more than four hydrogen molecules. ► The interation between metal and hydrogen molecule is electrostatic coulomb attraction. ► The electric field is induced by the charge transfer from metal 4s to metal 3d. ► The adsorbed hydrogen molecules which form supermolecule can further lower the binding energy.