Evaluation of Adsorption Equilibria for Hydrogen and Methane on Graphene

A graphene sample was prepared by the thermal reduction of graphite oxide. It was activated with potassium hydroxide to achieve a high special surface area of 1945 m2/g. Adsorption isotherms of hydrogen and methane were measured using the gravimetric method in the temperature range 253.15–353.15 K and at pressures of up to 2 MPa. Thermodynamic properties have been investigated to explore the adsorption interaction between the adsorbates and graphene. It is demonstrated that the isosteric heats of hydrogen and methane adsorption are in the range of 6 and 15 kJ/mol, respectively, approximating the values of other carbon materials. In addition, the generalized adsorption equilibrium isotherms of hydrogen and methane have been obtained for the prediction of adsorption equilibria. It may prove that the adsorption of hydrogen and methane on graphene may be primarily on the basis of physisorption.