Hydrogen adsorption on graphene sheets doped with group 8B transition metal: A DFT investigation

The binding of group 8B transition metals (TMs) on graphene sheet (GS) with hydrogen-terminated edges and the adsorption of hydrogen molecules on the pristine and TM-doped GSs were investigated using the density functional theory. The calculation showed that all TM atoms had strong binding with GS, in which the Os atom displayed the strongest interaction with GS. The hydrogen molecule displayed a weak interaction with pristine GS, whereas it had a strong interaction with TM-doped GSs, in which the Os-doped GS showed the strongest interaction with the hydrogen molecule. Moreover, the adsorptions of 2-5 hydrogen molecules adsorbed on Os-doped GS were also investigated, which three hydrogen molecules were adsorbed on the first adsorption layer of Os-doped GS. The increase in the adsorption abilities of hydrogen molecules onto the TM-doped GSs was due to the protruding structure and the TM induced charge transfer between TM-doped GSs and the hydrogen molecules. These observations showed that TM-doped GSs were highly sensitive toward hydrogen molecules. Therefore, the present results may be useful for the design of doping of TM on GS candidates, such as adsorbent and storage.