Hydrogen Storage Capacity of Carbon-Foams: Grand Canonical Monte Carlo Simulations

Hydrogen storage in the three-dimensional carbon foams is analyzed using classical grand canonical Monte Carlo simulations. The calculated storage capacities of the foams meet the material-based DOE targets and are comparable to the capacities of a bundle of well-separated similar diameter open nanotubes. The pore sizes in the foams are optimized for the best hydrogen uptake. The capacity depends sensitively on the C-H-2 interaction potential, and therefore, the results are presented for its ``weak'' and ``strong'' choices, to offer the lower and upper bounds for the expected capacities. Furthermore, quantum effects on the effective C-H-2 as well as H-2-H-2 interaction potentials are considered. We find that the quantum effects noticeably change the adsorption properties of foams and must be accounted for even at room temperature.