Characterization of a new phase of ammonia borane

Wendy J. Shaw, Mark Bowden, Abhi Karkamkar, Christopher J. Howard, David J. Heldebrant, Nancy J. Hess, John Linehan, Tom Autrey

Research output: Contribution to journalArticle

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Abstract

An uncharacterized phase of ammonia borane (AB) was previously identified while investigating the thermal aging of this hydrogen rich solid state material. This phase was identified as a key intermediate for the release of hydrogen from AB prompting the current characterization study. The new phase (AB*) was investigated extensively using in situ solid state MAS NMR spectroscopy, including 11B, 15N and 1H NMR. Single-pulse excitation, cross polarization and T1 relaxation experiments for all nuclei collectively demonstrated a significant increase in mobility of AB in the new phase compared to the room temperature phase of AB, consistent with a highly mobile solid. This implies a disruption of the extensive dihydrogen bonding network, allowing increased motional freedom. Complementary studies by in situ X-ray diffraction showed AB* to have the same crystal lattice as AB, but suggested an expanded lattice, providing support for increased mobility. NMR measurements of AB embedded into a mesoporous scaffold were also consistent with high mobility in AB*. These data suggest that a breakdown of the extensive hydrogen bonding network occurs before hydrogen can be released and will be an important factor in the practical use of AB as a hydrogen storage material.

Original languageEnglish
Pages (from-to)796-804
Number of pages9
JournalEnergy and Environmental Science
Volume3
Issue number6
DOIs
Publication statusPublished - 2010

Fingerprint

Boranes
Ammonia
ammonia
hydrogen
nuclear magnetic resonance
Hydrogen
Crystal lattices
Nuclear magnetic resonance
MAS
Thermal aging
Hydrogen storage
Scaffolds
Nuclear magnetic resonance spectroscopy
Hydrogen bonds
polarization
spectroscopy
X-ray diffraction
crystal
Polarization

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Chemistry
  • Pollution
  • Nuclear Energy and Engineering

Cite this

Shaw, W. J., Bowden, M., Karkamkar, A., Howard, C. J., Heldebrant, D. J., Hess, N. J., ... Autrey, T. (2010). Characterization of a new phase of ammonia borane. Energy and Environmental Science, 3(6), 796-804. https://doi.org/10.1039/b914338f

Characterization of a new phase of ammonia borane. / Shaw, Wendy J.; Bowden, Mark; Karkamkar, Abhi; Howard, Christopher J.; Heldebrant, David J.; Hess, Nancy J.; Linehan, John; Autrey, Tom.

In: Energy and Environmental Science, Vol. 3, No. 6, 2010, p. 796-804.

Research output: Contribution to journalArticle

Shaw, WJ, Bowden, M, Karkamkar, A, Howard, CJ, Heldebrant, DJ, Hess, NJ, Linehan, J & Autrey, T 2010, 'Characterization of a new phase of ammonia borane', Energy and Environmental Science, vol. 3, no. 6, pp. 796-804. https://doi.org/10.1039/b914338f
Shaw WJ, Bowden M, Karkamkar A, Howard CJ, Heldebrant DJ, Hess NJ et al. Characterization of a new phase of ammonia borane. Energy and Environmental Science. 2010;3(6):796-804. https://doi.org/10.1039/b914338f
Shaw, Wendy J. ; Bowden, Mark ; Karkamkar, Abhi ; Howard, Christopher J. ; Heldebrant, David J. ; Hess, Nancy J. ; Linehan, John ; Autrey, Tom. / Characterization of a new phase of ammonia borane. In: Energy and Environmental Science. 2010 ; Vol. 3, No. 6. pp. 796-804.
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