Hydrogen storage using carbon materials at room temperature

The hydrogen adsorption capacity of commercially available carbon materials with different nanostructures was measured at room temperature using an apparatus based on a volumetric method with an error of less than 0.04 wt% per one gram of sample. The obtained results suggest that nanosutures of the sample influence the hydrogen adsorption capacity. To confirm this hypothesis, we prepared nanostructured graphite from graphite powder using a mechanical milling process at a pressure of 2.0 x 10(-4) Pa. The untreated graphite adsorbed 0.02wt% of hydrogen at 6 MPa at room temperature, while 0.20 - 0.25 wt% of hydrogen can be repeatedly adsorbed by the nanostructured graphite. Measurements of the hydrogen adsorption rate at constant pressure and pore-size distribution imply that the hydrogen molecules are adsorbed through a diffusion process in pores with a diameter less than 1 nm.