Adsorption Properties and Structural Characterization of Activated Carbons and Nanocarbons

Abstract

Adsorption in porous solids at room or low temperature is one of the possible storage modes of hydrogen gas. The storage efficiency in these materials depends on their physical properties and characteristics, the most important being their adsorption capacity, porosity, density, and the endo- or exothermic character of the adsorption process. In particular, porous materials made of carbon nanotubes have been studied as potential hydrogen adsorbents in a large domain of pressures and temperatures. In this work, we present morphologic and structural characterizations of samples of carbon nanotube porous materials by the Brunauer, Emmett, and Teller method, transmission electronic microscopy, Raman spectroscopy, and helium density measurements. The adsorption of hydrogen in these materials is measured. A specific and new result of this measurement is the estimate of the excess adsorption, the relevant quantity for a correct determination of the storage capacity of porous materials.