Hydrogen desorption and adsorption measurements on graphite nanofibers

Graphite nanofibers were synthesized and their hydrogen desorption and adso rption properties are reported for 77 and 300 K. Catalysts were made by sev eral different methods including chemical routes, mechanical alloying, and gas condensation. The nanofibers were grown by passing ethylene and H-2 gas es over the catalysts at 600 degrees C. Hydrogen desorption and adsorption were measured using a volumetric analysis Sieverts' apparatus, and the grap hite nanofibers were characterized by transmission electron microscopy and Brunauer-Emmett-Teller surface area analysis. The absolute level of hydroge n desorption measured from these materials was typically less than the 0.01 H/C atom, comparable to other forms of carbon. (C) 1998 American Institute of Physics. [S0003-6951(98)04549-5].