Storage of molecular hydrogen in an ammonia borane compound at high pressure

Journal Article · Wed Jun 17 04:00:00 EDT 2009 · Proc. Natl. Acad. Sci. USA

DOI:https://doi.org/10.1073/pnas.0903511106· OSTI ID:1005663

Lin, Yu; Mao, Wendy L; Mao, Ho-kwang

We studied ammonia borane (AB), NH{sub 3}BH{sub 3}, in the presence of excess hydrogen (H{sub 2}) pressure and discovered a solid phase, AB(H{sub 2}){sub x}, where x {approx}1.3--2. The new AB-H{sub 2} compound can store an estimated 8--12 wt % molecular H{sub 2} in addition to the chemically bonded H{sub 2} in AB. This phase formed slowly at 6.2 GPa, but the reaction rate could be enhanced by crushing the AB sample to increase its contact area with H{sub 2}. The compound has 2 Raman H{sub 2} vibron peaks from the absorbed H{sub 2} in this phase: one ({nu}{sub 1}) at frequency 70 cm{sup -1} below the free H{sub 2} vibron, and the other ({nu}{sub 2}) at higher frequency overlapping with the free H{sub 2} vibron at 6 GPa. The peaks shift linearly over the pressure interval of 6--16 GPa with average pressure coefficients of d{nu}{sub 1}/dP = 4 cm{sup -1}/GPa and d{nu}{sub 2}/dP = 6 cm{sup -1}/GPa. The formation of the compound is accompanied by changes in the N-H and B-H stretching Raman peaks resulting from the AB interactions with H{sub 2} which indicate the structural complexity and low symmetry of this phase. Storage of significant amounts of additional molecular H{sub 2} in AB increases the already high hydrogen content of AB, and may provide guidance for developing improved hydrogen storage materials.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1005663
• Journal Information: Proc. Natl. Acad. Sci. USA, Journal Name: Proc. Natl. Acad. Sci. USA Journal Issue: (20) ; 05, 2009 Vol. 106; ISSN PNASA6; ISSN 0027-8424
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

08 HYDROGEN
AMMONIA
BORANES
CRUSHING
HYDROGEN
HYDROGEN STORAGE
INTERACTIONS
MATERIALS
PEAKS
PRESSURE COEFFICIENT
PRESSURE RANGE MEGA PA 10-100
REACTION KINETICS
SOLIDS
SYMMETRY