Hydrogen adsorption and desorption by carbon materials

Hydrogen adsorption and desorption in different carbon materials were determined at 77 and 296 K. Superactivated carbon having specific surface area of 3220 m2/g, adsorbed and desorbed 5 wt.% of hydrogen at 77 K and 1.3 wt.% of hydrogen at 296 K. The values were greater than those of conventional activated carbon, graphite nanofiber and single-walled carbon nanotube. The hydrogen adsorption capacities of the various carbon materials were given as a function of the specific surface area. According to the Clausius–Clapeyron equation, the heat of adsorption of the superactivated carbon was about 6 kJ/mol H2.