Abstract
Hydrogen burns pollution-free and may be produced from renewable energy resources. It is therefore an ideal candidate to replace fossil fuels as an energy carrier. However, the lack of a convenient and cost-effective hydrogen storage system greatly impedes the wide-scale use of hydrogen in both domestic and international markets. Although several hydrogen storage options exist, no approachsatisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. A material consisting exclusively of micropores with molecular dimensions could simultaneously meet all of the requirements for transportation use if the interaction energy for hydrogen was sufficiently strong to cause hydrogen adsorption at ambient temperatures. Small diameter (~1 nm)carbon single-wall nanotubes (SWNTs) are elongated micropores of molecular dimensions, and materials composed predominantly of SWNTs may prove to be the ideal adsorbent for ambient temperature storage of hydrogen. Last year we reported that hydrogen could be adsorbed on arc-generated soots containing 12 .ANG. diameter nanotubes at temperatures in excess of 285K. In this past year we have learnedthat such adsorption does not occur on activated carbon materials, and that the cobalt nanoparticles present in our arc-generated soots are not responsible for the hydrogen which is stable at 285K. These results indicate that enhanced adsorption forces within the internal cavities of the SWNTs are active in stabilizing hydrogen at elevated temperatures. This enhanced stability could lead toeffective hydrogen storage under ambient temperature conditions. In the past year we have also demonstrated that single-wall carbon nanotubes in arc-generated soots maybe selectively opened by oxidation in H2O resulting in improved hydrogen adsorption, and we have estimated experimentally that the amount of hydrogen stored is~10% of the nanotube weight. We have also correlated hydrogenadsorption capacities with nanotube densities, prepared cobalt-doped carbon targets for high-yield and potentially low-cost production of SWNTs, and are the first to demonstrate the use of concentrated solar radiation for the formation fof SWNTs by a new and potentially less expensive route.
Original language | American English |
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Pages | Vol. II: 747-763 |
Number of pages | 17 |
State | Published - 1996 |
Event | 1996 U.S. DOE Hydrogen Program Review - Miami, Florida Duration: 1 May 1996 → 2 May 1996 |
Conference
Conference | 1996 U.S. DOE Hydrogen Program Review |
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City | Miami, Florida |
Period | 1/05/96 → 2/05/96 |
NREL Publication Number
- NREL/CP-22547