Hydrogen adsorption in nanotube and cylindrical pore: A grand canonical Monte Carlo simulation study

Physisorption of targeted amount of hydrogen within carbonaceous material is a formidable task. Even though at 80 K adsorption is satisfactory but at 298 K storing desirable amount of hydrogen is difficult. Here we report grand canonical monte carlo simulation of hydrogen adsorption within two different cylindrical pores in the temperature range 60–298 K and in the pressure range 1–500 bar. In one we construct a cylindrical pore (CP) of ≈2.0 nm diameter by removing carbon atoms from the center of stacked graphene sheets. In the other single walled carbon nanotube (SWCNT) of similar diameter is used for the adsorption. In all of our simulations intermolecular hydrogen interactions are modeled using the classical Silvera-Goldman potential, which contains both Lennard-Jones and electrostatic sites. Total amount of adsorbed hydrogen is always greater in SWCNT (adsorbed both inside and outside the wall) than in CPs, however amount of hydrogen adsorbed inside SWCNT only is always smaller than that inside CP. Surface defects created during removal of carbon atoms in CP results in almost 2 wt% increase in uptake compared to SWCNT.