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Title: Carbon Aerogels – Hot Catchers for Exotic Isotopes and/or Molecular Species

Authors:
 [1]
  1. InnoSense LLC
Publication Date:
Research Org.:
InnoSense LLC, 2531 West 237th Street, Suite 127, Torrance, CA 90505-5245
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Org.:
InnoSense LLC and Argonne National Laboratory
OSTI Identifier:
1148820
Report Number(s):
3061-Final-DOE Hot Catchers II
Job #3061
DOE Contract Number:
SC0004265
Type / Phase:
SBIR
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; Rare Isotope Capture, Solid Catchers, Tungsten-coated Silica Aerogels, Carbon Aerogels, Porous Carbon Aerogels as Solid Catchers, Open Interconnected Porosity for Capturing Rare Isotopes

Citation Formats

Sampathkumaran, Uma. Carbon Aerogels – Hot Catchers for Exotic Isotopes and/or Molecular Species. United States: N. p., 2014. Web.
Sampathkumaran, Uma. Carbon Aerogels – Hot Catchers for Exotic Isotopes and/or Molecular Species. United States.
Sampathkumaran, Uma. Mon . "Carbon Aerogels – Hot Catchers for Exotic Isotopes and/or Molecular Species". United States. doi:.
@article{osti_1148820,
title = {Carbon Aerogels – Hot Catchers for Exotic Isotopes and/or Molecular Species},
author = {Sampathkumaran, Uma},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Aug 04 00:00:00 EDT 2014},
month = {Mon Aug 04 00:00:00 EDT 2014}
}

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  • This effort is focused on the design of new nanostructured carbon-based materials that meet the DOE 2010 targets for on-board vehicle hydrogen storage. Carbon aerogels (CAs) are a unique class of porous materials that possess a number of desirable structural features for the storage of hydrogen, including high surface areas (over 3000 m{sup 2}/g), continuous and tunable porosities, and variable densities. In addition, the flexibility associated with CA synthesis allows for the incorporation of modifiers or catalysts into the carbon matrix in order to alter hydrogen sorption enthalpies in these materials. Since the properties of the doped CAs can bemore » systematically modified (i.e. amount/type of dopant, surface area, porosity), novel materials can be fabricated that exhibit enhanced hydrogen storage properties. We are using this approach to design new H{sub 2} sorbent materials that can storage appreciable amounts of hydrogen at room temperature through a process known as hydrogen spillover. The spillover process involves the dissociative chemisorption of molecular hydrogen on a supported metal catalyst surface (e.g. platinum or nickel), followed by the diffusion of atomic hydrogen onto the surface of the support material. Due to the enhanced interaction between atomic hydrogen and the carbon support, hydrogen can be stored in the support material at more reasonable operating temperatures. While the spillover process has been shown to increase the reversible hydrogen storage capacities at room temperature in metal-loaded carbon nanostructures, a number of issues still exist with this approach, including slow kinetics of H{sub 2} uptake and capacities ({approx} 1.2 wt% on carbon) below the DOE targets. The ability to tailor different structural aspects of the spillover system (i.e. the size/shape of the catalyst particle, the catalyst-support interface and the support morphology) should provide valuable mechanistic information regarding the critical aspects of the spillover process (i.e. kinetics of hydrogen dissociation, diffusion and recombination) and allow for optimization of these materials to meet the DOE targets for hydrogen storage. In a parallel effort, we are also designing CA materials as nanoporous scaffolds for metal hydride systems. Recent work by others has demonstrated that nanostructured metal hydrides show enhanced kinetics for reversible hydrogen storage relative to the bulk materials. This effect is diminished, however, after several hydriding/dehydriding cycles, as the material structure coarsens. Incorporation of the metal hydride into a porous scaffolding material can potentially limit coarsening and, therefore, preserve the enhanced kinetics and improved cycling behavior of the nanostructured metal hydride. Success implementation of this approach, however, requires the design of nanoporous solids with large accessible pore volumes (> 4 cm{sup 3}/g) to minimize the gravimetric and volumetric capacity penalties associated with the use of the scaffold. In addition, these scaffold materials should be capable of managing thermal changes associated with the cycling of the incorporated metal hydride. CAs are promising candidates for the design of such porous scaffolds due to the large pore volumes and tunable porosity of aerogel framework. This research is a joint effort with HRL Laboratories, a member of the DOE Metal Hydride Center of Excellence. LLNL's efforts have focused on the design of new CA materials that can meet the scaffolding requirements, while metal hydride incorporation into the scaffold and evaluation of the kinetics and cycling performance of these composites is performed at HRL.« less
  • This document and the accompanying manuscript summarize the technical accomplishments of our one-year LDRD-ER effort. Hydrogen storage and hydrogen fuel cells are important components of the 2003 Hydrogen Fuel Initiative focused on the reduction of America's dependence on oil. To compete with oil as an energy source, however, one must be able to transport and utilize hydrogen at or above the target set by DOE (6 wt.% H{sub 2}) for the transportation sector. Other than liquid hydrogen, current technology falls well short of this DOE target. As a result, a variety of materials have recently been investigated to address thismore » issue. Carbon nanostructures have received significant attention as hydrogen storage materials due to their low molecular weight, tunable microporosity and high specific surface areas. For example, the National Renewable Energy Laboratory (NREL) achieved 5 to 10 wt.% H{sub 2} storage using metal-doped carbon nanotubes. That study showed that the intimate mix of metal nanoparticles with graphitic carbon resulted in the unanticipated hydrogen adsorption at near ambient conditions. The focus of our LDRD effort was the investigation of metal-doped carbon aerogels (MDCAs) as hydrogen storage materials. In addition to their low mass densities, continuous porosities and high surface areas, these materials are promising candidates for hydrogen storage because MDCAs contain a nanometric mix of metal nanoparticles and graphitic nanostructures. For FY04, our goals were to: (1) prepare a variety of metal-doped CAs (where the metal is cobalt, nickel or iron) at different densities and carbonization temperatures, (2) characterize the microstructure of these materials and (3) initiate hydrogen adsorption/desorption studies to determine H2 storage properties of these materials. Since the start of this effort, we have successfully prepared and characterized Ni- and Co-doped carbon aerogels at different densities and carbonization temperatures. The bulk of this work is described in the attached manuscript entitled 'Formation of Carbon Nanostructures in Cobalt- and Nickel- Doped Carbon Aerogels'. This one-year effort has lead to our incorporation into the DOE Carbon-based Hydrogen Storage Center of Excellence at NREL, with funding from DOE's Energy Efficiency and Renewable Energy (EERE) Program starting in FY05.« less
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