IN SITU SYNTHESIS OF LiNH2 FROM Li METAL AND LIQUID NH3 IN
NANOPOROUS CARBON: A NEW NANOCONFINEMENT APPROACH
Natchapol Poonyayant1,*, Vitalie Stavila2,#, Natee Angboonpong1, Pasit Pakawatpanurut1,3,
Lennie Klebanoff2
1
Physical Chemistry Program, Center for Alternative Energy and Department of Chemistry,
Faculty of Science, Mahidol University, Bangkok, Thailand
2
Sandia National Laboratories, Livermore, CA 94551
3
Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University,
Bangkok, Thailand
*e-mail: natchapolp@gmail.com, #e-mail: vnstavi@sandia.gov
Abstract
LiNH2 is one of the promising hydrogen storage materials with high hydrogen
capacity and potential for reversibility. However, the bulk material desorbs hydrogen only at
high temperatures and also releases ammonia as a by-product. Nanoconfinement of LiNH2 in
nanoporous carbon was hypothesized to solve these problems by improving the kinetics of
hydrogen release while also suppressing the ammonia formation. A novel in situ synthesis of
LiNH2 confined in nanoporous carbon was demonstrated in this study. Powder X-Ray
Diffraction indicates that the only crystalline phase present is LiNH2. Surface area
measurements by porosimetry confirm the confinement of LiNH2 inside the pore of
nanoporous carbon. Elemental analysis showed a chemical composition of Li0.7N1H2.94 which
suggests that the product was solvated with ammonia. Thermal decomposition of
nanoconfined LiNH2 was monitored using the Thermo Gravimetric Analysis/Differential
Scanning Calorimetry/Mass Spectrometry analysis. The nanoconfined LiNH2 releases
hydrogen at 75oC lower than bulk. This work demonstrates a new versatile approach towards
metal hydride nanoconfinement which does not involve melting or vaporizing the material.
Acknowledgements: The authors acknowledge Ken Stewart and Joe Cordaro (Sandia
National Laboratories) for their technical assistance. Poonyayant, Angboonpong, and
Pakawatpanurut acknowledge support from the Development and Promotion of Science and
Technology talents project, the Center of Excellence for Innovation in Chemistry (PERCHCIC), and the Distinction Program, Faculty of Science, Mahidol University. This work was
supported by the U.S. Department of Energy, Office of Efficiency and Renewable Energy,
under Award Nos. DE-AC04-94AL8500. Partial support for this work from The Boeing
Company is also greatly appreciated. The authors thank Joe Breit from Boeing for his
support of this work.
Keywords: LiNH2, nanoconfinement, in situ synthesis, hydrogen storage
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