Reversibility of the hydrogen desorption from NaBH4 by confinement in nanoporous carbon

Ngene, Peter; Berg, Roy van den; Verkuijlen, M.H.W.; Jong, Krijn P. de; Jongh, Petra E. de

doi:10.1039/c1ee01481a

Cited by 115 publications

(143 citation statements)

References 57 publications

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“…S19, ESI †), suggesting the formation of Na 2 B 12 H 12 as earlier reported (for example ref. 10). Also slight shift towards the original value occurred in the ex situ rehydrogenated samples due to partial reversibility of these samples.…”

Section: Discussionmentioning

confidence: 99%

“…Also slight shift towards the original value occurred in the ex situ rehydrogenated samples due to partial reversibility of these samples. 10,30 However detailed quantification of the phases was not possible due to the lack of data on other standard reference materials like Na 2 B 12 H 12 during the XRS measurements.…”

Section: Discussionmentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12][13][14][15] These strategies generally led to an improvement in their hydrogen sorption properties. However, for practical application further improvement of these materials is required.…”

Section: Introductionmentioning

confidence: 99%

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In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Miedema

Ngene

Eerden

et al. 2014

Phys. Chem. Chem. Phys.

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Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de-and re-hydrogenation of nanoconfined lithium borohydride (LiBH 4 ) and therefore we can possibly identify the de-and re-hydrogenation pathways. In the XRS of nanoconfined LiBH 4 at different points in the de-and re-hydrogenation, we identified phases that lead to the conclusion that de-and re-hydrogenation pathways in nanoconfined LiBH 4 are different from bulk LiBH 4 : intercalated lithium (LiC x ), boron and lithium hydride were formed during de-hydrogenation, but as well Li 2 B 12 H 12 was observed indicating that there is possibly some bulk LiBH 4 present in the nanoconfined sample LiBH 4 -C as prepared.Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH 4 -C nanocomposites can be partially rehydrogenated to about 90% of Li 2 B 12 H 12 and 2-5% of LiBH 4 at a mild condition of 1 bar H 2 and 350 1C. This suggests that re-hydrogenation occurs via the formation of Li 2 B 12 H 12 . Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Miedema

Ngene

Eerden

et al. 2014

Phys. Chem. Chem. Phys.

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“…51 Recent research shows that addition of nano-porous carbon facilities hydrogen uptake for bulk NaBH 4 significantly. 53 In order to address the possible effect of sodium fluoride, NaF, on the hydrogen storage properties a sample of NaBH 4 -NaF (1 : 0.25, S6) was investigated. The first desorption of S6 resembles pure NaBH 4 with a total gas release of 4.9 wt% and 1.1 wt% in both second and third desorption, see Fig.…”

Section: Sieverts Measurementsmentioning

confidence: 99%

Hydrogen–fluorine exchange in NaBH4–NaBF4

Rude

Filsø

D’Anna

et al. 2013

Phys. Chem. Chem. Phys.

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a Hydrogen-fluorine exchange in the NaBH 4 -NaBF 4 system is investigated using a range of experimental methods combined with DFT calculations and a possible mechanism for the reactions is proposed. Fluorine substitution is observed using in situ synchrotron radiation powder X-ray diffraction (SR-PXD) as a new Rock salt type compound with idealized composition NaBF 2 H 2 in the temperature range T = 200 to 215 1C. Combined use of solid-state 19 F MAS NMR, FT-IR and DFT calculations supports the formation of a BF 2 H 2 complex ion, reproducing the observation of a 19 F chemical shift at 144.2 ppm, which is different from that of NaBF 4 at 159.2 ppm, along with the new absorption bands observed in the IR spectra. After further heating, the fluorine substituted compound becomes X-ray amorphous and decomposes to NaF at B310 1C. This work shows that fluorine-substituted borohydrides tend to decompose to more stable compounds, e.g. NaF and BF 3 or amorphous products such as closo-boranes, e.g. Na 2 B 12 H 12 . The NaBH 4 -NaBF 4 composite decomposes at lower temperatures (300 1C) compared to NaBH 4 (476 1C), as observed by thermogravimetric analysis. NaBH 4 -NaBF 4 (1 : 0.5) preserves 30% of the hydrogen storage capacity after three hydrogen release and uptake cycles compared to 8% for NaBH 4 as measured using Sievert's method under identical conditions, but more than 50% using prolonged hydrogen absorption time. The reversible hydrogen storage capacity tends to decrease possibly due to the formation of NaF and Na 2 B 12 H 12 . On the other hand, the additive sodium fluoride appears to facilitate hydrogen uptake, prevent foaming, phase segregation and loss of material from the sample container for samples of NaBH 4 -NaF.

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“…It has been reported that nanoconfinement of NaBH 4 in nanoporous scaffolds is an effective way to improve the kinetic and/or thermodynamic properties of the NaBH 4 material. 37,38 The fabrication of NaBH 4 in the host materials is not easy, however, as the melting point of NaBH 4 is quite close to the decomposition temperature, and the solubility of NaBH 4 in organic solvent is poor. 39 Because of the low melting temperature and low hydrazine desorption temperature, these sodium borohydride hydrazinate complexes can be easily infiltrated into a nanoporous scaffold via a simple melt impregnation method.…”

Section: Thermal Decomposition Behaviormentioning

confidence: 99%

Sodium borohydride hydrazinates: synthesis, crystal structures, and thermal decomposition behavior

Mao

Guo

et al. 2015

J. Mater. Chem. A

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. (2015). Sodium borohydride hydrazinates: synthesis, crystal structures, and thermal decomposition behavior. Journal of Materials Chemistry A, 3 (21), 11269-11276. Sodium borohydride hydrazinates: synthesis, crystal structures, and thermal decomposition behavior AbstractMetallic borohydride hydrazinates are novel boron-and nitrogen-based materials that appear to be promising candidates for chemical hydrogen storage. Herein, sodium borohydride hydrazinates, including NaBH 4 ·N2H 4 and NaBH 4 ·2N 2 H 4 , were synthesized via a facile solution synthesis approach based on the solid-liquid reaction between NaBH 4 and hydrazine in tetrahydrofuran (THF) solution. The crystal structure of NaBH 4 ·2N 2 H 4 was solved to a monoclinic structure with unit cell parameters a = 8.4592(2) Å, b = 11.7131(2) Å, c = 6.4584(1) Å, and β = 100.0777(14)°, with space group A1a1 (9). Each Na + ion interacts with four neighboring N 2 H 4 molecules, leading to the formation of Na 4 [N 2 H 4 ] 4 4+ cationic chains along the a direction. Such cationic chains are surrounded by BH 4 − anions. The NaBH 4 ·xN 2 H 4 (x = 1, 2) was characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectroscopy (MS) to obtain a full picture of the relationship of the structure to the decomposition, which will be useful for future work on borohydride hydrazinates or the study of other B-N materials. Furthermore, magnesium borohydride hydrazinates were synthesized by ball milling the sodium borohydride hydrazinates with magnesium borohydride, and their thermal decomposition was investigated as well. differential scanning calorimetry (DSC), and mass spectroscopy (MS) to obtain a full picture of the relationship of the structure to the decomposition, which will be useful for future work on borohydride hydrazinates or the study of other B-N materials.Furthermore, magnesium borohydride hydrazinates were synthesized by ball milling the sodium borohydride hydrazinates with magnesium borohydride, and their thermal decomposition was investigated as well.

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Reversibility of the hydrogen desorption from NaBH4 by confinement in nanoporous carbon

Cited by 115 publications

References 57 publications

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites

Hydrogen–fluorine exchange in NaBH4–NaBF4

Sodium borohydride hydrazinates: synthesis, crystal structures, and thermal decomposition behavior

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