Prediction of Hydrogen Adsorption Properties in Expanded Graphite Model and in Nanoporous Carbon

This paper calculates that the theoretical hydrogen uptake in nanoporous carbons is close to 0.5 wt % at 298 K and 5 MPa, higher than most reported values in activated carbons. The isosteric heats of adsorption for nanoporous carbons and for an expanded graphite model are between 14 and 18 kJ/mol, close to the suitable energy range for practical hydrogen storage (15-40 kJ/mol). Over the density ranges examined, total hydrogen adsorption can be improved by increasing the volume available for adsorption in amorphous carbons. These calculations are performed by using an efficient and accurate method. This method can reproduce previous, more computational intensive calculations in the expanded graphite model yet is readily applicable to more complex geometries. The limitations of this method are discussed carefully; under conditions given above, these limitations are minimal.