Dense hydrogen adsorption on carbon subnanopores at 77 K

Hydrogen adsorption measurements on two types of different carbon nanomaterials were carried out at 77 K up to hydrogen pressures of 2 MPa using the volumetric method modified for low-temperature experiments. The adsorption property was concluded as dense hydrogen physisorption in subnanometer-sized pores because of the Langmuir-type isotherm, reversible adsorption/desorption, and large hydrogen uptake exceeding 2 wt %. The estimated density of adsorbed hydrogen was comparable to the density of bulk liquid hydrogen, indicating that hydrogen filling would be attainable when both the chemical potential of hydrogen and adsorption potential of carbon were optimized. (C) 2003 American Institute of Physics.