Comparison of theoretical methods of the hydrogen storage capacities of nanoporous carbons

Abstract

The hydrogen storage capacities of nanoporous carbons, simulated as graphene slit-shaped pores, have been calculated using simple theoretical methods that do not involve computationally expensive calculations. The theoretical methods calculate the storage of hydrogen molecules on a solid porous material by using the Equation Of State, EOS, of the hydrogen gas and the interaction potential energy of H2 with the surfaces of the pores of the material. Calculations have been carried out using the same interaction potential energy and empirical EOS. The interaction potential energy is obtained from calculations of H2 on graphene, using a DFT-based method that includes the dispersion interactions. The storage capacities have been calculated as a function of pressure in the range 0.1–25 MPa, of pore width in the range 4.7–20 Å and at 80.15 and 298.15 K. The storage capacities obtained with the methods are compared and the advantages and limitations of the methods are discussed, as well as the storage capacities predicted by the methods for wide pores. These simple theoretical methods are useful to design novel materials for hydrogen storage.