ChemInform Abstract: α‐ and β‐Na2[BH4][NH2]: Two Modifications of a Complex Hydride in the System NaNH2—NaBH4; Syntheses, Crystal Structures, Thermal Analyses, Mass and Vibrational Spectra.

Somer, M.; Acar, Selcuk; Koz, Cevriye; Kokal, Ilkin; Hoehn, Peter; Cardoso‐Gil, Raúl; Aydemir, Umut; Akselrud, Lev

doi:10.1002/chin.201014007

Cited by 4 publications

(10 citation statements)

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“…The decomposition products are reported to be NaH, Na and an amorphous unidentified white solid. In fact, Na2BNH6 releases hydrogen while molten between 300 °C and 400 °C yielding NaH, Na and a grey amorphous powder [68]. On addition of excess amide (≥2:1 NaNH2:NaBH4), Na3BN2 becomes the sole product.…”

Section: Chemical Modificationmentioning

confidence: 99%

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

2015

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Abstract:The development of new practical hydrogen storage materials with high volumetric and gravimetric hydrogen densities is necessary to implement fuel cell technology for both mobile and stationary applications. NaBH4, owing to its low cost and high hydrogen density (10.6 wt%), has received extensive attention as a promising hydrogen storage medium. However, its practical use is hampered by its high thermodynamic stability and slow hydrogen exchange kinetics. Recent developments have been made in promoting H2 release and tuning the thermodynamics of the thermal decomposition of solid NaBH4. These conceptual advances offer a positive outlook for using NaBH4-based materials as viable hydrogen storage carriers for mobile applications. This review summarizes contemporary progress in this field with a focus on the fundamental dehydrogenation and rehydrogenation pathways and properties and on material design strategies towards improved kinetics and thermodynamics such as catalytic doping, nano-engineering, additive destabilization and chemical modification.

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Section: Chemical Modificationmentioning

confidence: 99%

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

2015

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“…The NH 2 groups are shown as large gray spheres since the exact orientation of N−H bonds in them is not known. 15 Figure 3 represents the evolution of the 1 H NMR spectrum for Na 2 (BH 4 )(NH 2 ) with temperature. At low temperatures, the spectrum looks like a superposition of two lines with different widths.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Furthermore, Na 2 (BH 4 )-(NH 2 ) shows a high electrochemical stability. 13 The cubic α-Na 2 (BH 4 )(NH 2 ) crystallizes in the K 3 SO 4 F-type structure (space group Pm3̅ m) 14,15 with two-thirds occupancy of the corresponding Na sublattice. The high concentration of vacancies in the cation sublattice is believed to facilitate ionic conductivity.…”

mentioning

confidence: 99%

“…Besides the α-phase of Na 2 (BH 4 )(NH 2 ), the orthorhombic β modification (space group Pbcm) of this compound is also known. 15 However, the β phase can be formed from the α phase only after long annealing (10 days) at temperatures 340−370 K. 15 To understand the nature of high ionic conductivity in complex hydrides, it is important to study the relations between the crystal structure, anion rotational dynamics, and cation mobility. It should be noted that, for a number of borohydride-based compounds showing high Li-ion diffusivity, the fast BH 4 reorientations have also been observed.…”

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confidence: 99%

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Nuclear Magnetic Resonance Study of Atomic Motion in the Mixed Borohydride–Amide Na₂(BH₄)(NH₂)

et al. 2014

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To study the reorientational motion of the anions and the translational diffusion of Na + cations in the mixed borohydride−amide Na 2 (BH 4 )(NH 2 ) showing fast-ion conduction, we have measured the 1 H, 11 B, and 23 Na NMR spectra and spin−lattice relaxation rates in this compound over broad ranges of temperature (6−480 K) and the resonance frequency (14−132.3 MHz). At low temperatures (T < 190 K), the proton spin−lattice relaxation rate is governed by fast reorientations of BH 4 groups. This reorientational process can be satisfactorily described in terms of a Gaussian distribution of the activation energies with the average E a value of 74 ± 7 meV. Above 250 K, the measured proton spin−lattice relaxation rate originates from two other (slower) reorientational jump processes characterized by the average activation energies of 340 ± 9 meV and 559 ± 7 meV. The 23 Na spin− lattice relaxation data in the high-temperature region are governed by translational diffusion of Na + ions, which is consistent with high Na-ion conductivity in Na 2 (BH 4 )(NH 2 ).

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“…The corresponding NaNH 2 −NaBH 4 system promises to be more appropriate for the development of new hydrogen storage materials, with the price one tenth of that of LiBH 4 . 41,42 Furthermore, the electronegativity of metal Li and Na are almost the same, 1.0 and 0.9, respectively. We did a lot of investigations on the dehydrogenation performance of NaNH 2 −NaBH 4 (2/1 molar ratio), such as the desorption property of pristine 43 and Co− B-, 44 Ni−Co−B-, 45,46 and Mg−Co−B-doped NaNH 2 −NaBH 4 (2/1 molar ratio) hydrogen storage materials.…”

Section: ■ Introductionmentioning

confidence: 94%

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH₂–NaBH₄ Hydrogen Storage Composite

Pei

Bai

Wang

et al. 2017

ACS Appl. Mater. Interfaces

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The lightweight compound material NaNH-NaBH is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH-NaBH (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H, NH, BH, and N in the heating process from room temperature to 400 °C, and possibly the impurity gas BH also exists. The TG/DTA analyses show that the composite NaNH-NaBH (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na(NH)BH hydride decomposes into NaBN and H (200-350 °C); (2) remaining Na(NH)BH reacts with NaBH and NaBN, generating Na, BN, NH, N, and H (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.

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ChemInform Abstract: α‐ and β‐Na₂[BH₄][NH₂]: Two Modifications of a Complex Hydride in the System NaNH₂—NaBH₄; Syntheses, Crystal Structures, Thermal Analyses, Mass and Vibrational Spectra.

Cited by 4 publications

References 1 publication

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

Nuclear Magnetic Resonance Study of Atomic Motion in the Mixed Borohydride–Amide Na₂(BH₄)(NH₂)

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH₂–NaBH₄ Hydrogen Storage Composite

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ChemInform Abstract: α‐ and β‐Na2[BH4][NH2]: Two Modifications of a Complex Hydride in the System NaNH2—NaBH4; Syntheses, Crystal Structures, Thermal Analyses, Mass and Vibrational Spectra.

Cited by 4 publications

References 1 publication

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

Nuclear Magnetic Resonance Study of Atomic Motion in the Mixed Borohydride–Amide Na2(BH4)(NH2)

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2–NaBH4 Hydrogen Storage Composite

Contact Info

Product

Resources

About

ChemInform Abstract: α‐ and β‐Na₂[BH₄][NH₂]: Two Modifications of a Complex Hydride in the System NaNH₂—NaBH₄; Syntheses, Crystal Structures, Thermal Analyses, Mass and Vibrational Spectra.

Nuclear Magnetic Resonance Study of Atomic Motion in the Mixed Borohydride–Amide Na₂(BH₄)(NH₂)

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH₂–NaBH₄ Hydrogen Storage Composite