An emerging hypothesis to explain hydrogen storage in graphite nanofibers (GNF) is that defects, dislocations, and/or terminal carbons lead to increased hydrogen storage via hydrogen intercalation into the graphite lattice. Studies have been conducted to develop methods that expand the graphite lattice a priori in nano-carbonaceous materials, via carbon exfoliation. A method derived from well-established techniques to exfoliate graphite, in which intercalation of graphite is followed by a thermal shock to expand the interplanar spacing between the graphitic layers, is presented. The exfoliation technique plays a large role in the resulting GNF microstructure, surface area, and hydrogen storage properties. Variations in preparation conditions expand the GNF lattice from 3.4 to over 500 A. Increased surface area correlates with low temperature physisorption of hydrogen at 77 K, while dislocations in the graphitic structure correlated with ambient temperature adsorption. Selective exfoliation of a nanocarbon is a means to control the relative binding energy of the hydrogen interaction with the carbon structure and thus vary the operative adsorption temperature. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)