Volumetric adsorption isotherms of hydrogen on exfoliated graphite

We report volumetric adsorption isotherm measurements of molecular hydrogen on a good quality exfoliated graphite foam substrate (H$_{\mathrm{2}}$/gr) at temperatures above 20K performed with the goal of understanding the initial stages of adsorption on this two-dimensional (2d) system at temperatures well above the known phase transitions of the monolayer H$_{\mathrm{2}}$/gr. We obtain the isosteric heat of adsorption of H$_{\mathrm{2}}$/gr as a function of coverage. On the very low coverage region below 10{\%} of a monolayer we are currently working towards obtaining (1) a measurement of the binding energy of non-interacting H$_{\mathrm{2}}$ on graphite, (2) the highest coverage at which heterogeneities in the substrate produce deviations from a linear dependence of the equilibrium 3d pressure vs. coverage (Henry's law), and (3) the 2d van der Waals coefficients of the weakly interacting 2d gas of H$_{\mathrm{2}}$ molecules We compare our results to the ones obtained with similar measurements using carbon nanotube bundles as the substrate.