Maximizing Physisorption of Hydrogen by Metal-Doping of Graphene Derived Carbon*

Hydrogen, as a fuel for fuel-cell vehicles, is limited by the ability to densely pack large quantities of hydrogen at low pressures. Material-based storage using graphene as an adsorption substrate is a promising alternative as the hydrogen gas can interact with the graphene planes by weak Van der Waals forces. Graphene is lightweight and has a surface area of 2630 m²/g and hydrogen can be reversibly adsorbed on the graphene through physisorption, potentially allowing an increase in volumetric hydrogen density over other carbon sorbents. This research seeks to further maximize hydrogen adsorption onto graphene through decoration of the carbon surface with metals. Graphene derived carbon was functionalized with varying amounts of nickel and copper metals. The size and amounts of metal clusters was analyzed with scanning electron microscopy and x-ray fluorescence. We found a 15 to 20 percent increase in hydrogen adsorption over pristine material for a copper-functionalized material with 2285 m²/g surface area and a nickel functionalized material with 2325 m²/g at room temperature and 1 bar.