Thermodynamic destabilization and reaction kinetics in light metal hydride systems

Vajo, John J.; Salguero, Tina T.; Gross, Adam F.; Skeith, Sky L.; Olson, G. L.

doi:10.1016/j.jallcom.2007.02.080

Cited by 146 publications

(202 citation statements)

References 20 publications

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“…First MgH 2 desorbs and forms Mg. After an incubation period the LiBH 4 decomposes leading simultaneously to the formation of LiH and MgB 2 with additional hydrogen release. 15,16 It has been demonstrated that MgB 2 formation is the key for the reversibility. 14,17 To reach the DOE requirements, the dehydrogenation/hydrogenation of the system needs to be improved to reduce the incubation period as well as the overall reaction kinetics.…”

Section: Introductionmentioning

confidence: 99%

“…14 The organometallic compound titanium isopropoxide ͑Ti-iso͒ was found to be one of the most efficient additives for this system. 15,16 Additionally the initial activation and mixing of materials and additives by high energy ball milling is also contributing strongly to kinetic improvement. 15,16 The characterization of the additives in the initial and cycled composites was a first step toward understanding the function of additives and the mechanism of H 2 sorption reactions.…”

Section: Introductionmentioning

confidence: 99%

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Combined x-ray photoelectron spectroscopy and scanning electron microscopy studies of the LiBH4–MgH2 reactive hydride composite with and without a Ti-based additive

Deprez

Muñoz‐Márquez

Haro

et al. 2011

Journal of Applied Physics

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A detailed electronic and microstructural characterization is reported for the LiBH4–MgH2 reactive hydride composite system with and without titanium isopropoxide as additive. Surface characterization by x-ray photoelectron spectroscopy combined to a morphological study by scanning electron microscopy as well as elemental map composition analysis by energy dispersive x-ray emission are presented in this paper for the first time for all sorption steps. Although sorption reactions are not complete at the surface due to the unavoidable superficial oxidation, it has been shown that the presence of the additive is favoring the heterogeneous nucleation of the MgB2 phase. Ti-based phases appear in all the samples for the three sorption steps well dispersed and uniformly distributed in the material. Li-based phases are highly dispersed at the surface while the Mg-based ones appear, either partially covered by the Li-based phases, or forming bigger grains. Ball milling is promoting mixing of phases and a good dispersion of the additive what favors grain refinement and heterogeneous reactions at the interfaces.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combined x-ray photoelectron spectroscopy and scanning electron microscopy studies of the LiBH4–MgH2 reactive hydride composite with and without a Ti-based additive

Deprez

Muñoz‐Márquez

Haro

et al. 2011

Journal of Applied Physics

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“…An example [84,[89][90][91] of such an approach is illustrated in Figure 13 for a LiBH 4 +MgH 2 -destabilized system exhibiting a drop in the enthalpy of decomposition and decomposition temperature by 23 kJ mol À1 H 2 and 240 K, correspondingly, compared to pure LiBH 4 . [90,92] The number of possible destabilization reactions significantly exceeds the number of existing chemical hydrides, which offers a promising avenue for developing a viable hydrogen storage system. A large number of destabilization reactions have already been studied both theoretically and experimentally; some of the results are presented in Figure 14.…”

Section: Hydrogen Storage Materialsmentioning

confidence: 99%

“…Reduction in the decomposition temperature of destabilized LiBH 4 + MgH 2 system by 240 K comparing to pure LiBH 4 . [90] Figure 12. A correlation of the temperature, T dec , at which thermal decomposition of binary hydrides MH 2 to the constituent elements proceeds, and the corresponding standard redox potential of the M n + /M 0 redox pair in acidic aqueous solutions, E 0 .…”

Section: Hydrogen Storage Materialsmentioning

confidence: 99%

Functional Materials for Sustainable Energy Technologies: Four Case Studies

Кузнецов

Edwards

2010

ChemSusChem

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The critical topic of energy and the environment has rarely had such a high profile, nor have the associated materials challenges been more exciting. The subject of functional materials for sustainable energy technologies is demanding and recognized as a top priority in providing many of the key underpinning technological solutions for a sustainable energy future. Energy generation, consumption, storage, and supply security will continue to be major drivers for this subject. There exists, in particular, an urgent need for new functional materials for next‐generation energy conversion and storage systems. Many limitations on the performances and costs of these systems are mainly due to the materials′ intrinsic performance. We highlight four areas of activity where functional materials are already a significant element of world‐wide research efforts. These four areas are transparent conducting oxides, solar energy materials for converting solar radiation into electricity and chemical fuels, materials for thermoelectric energy conversion, and hydrogen storage materials. We outline recent advances in the development of these classes of energy materials, major factors limiting their intrinsic functional performance, and potential ways to overcome these limitations.

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“…In order to overcome the thermodynamic and kinetic limitations of the thermal decomposition of borohydrides, several novel strategies, such as catalytic doping, 13 nano-engineering, 14 additive destabilization, 15 and chemical modification, 16 have been employed in the past decade, One of the most fascinating strategies is to combine the borohydrides with H δ+ enriched nitrogen-containing compounds such as amide, guanidinium, and NH 3 to form new boron and nitrogen based compounds or composites. [17][18][19][20][21][22][23] The B-N-H materials contain both hydridic and protic hydrogens, and are therefore expected to release hydrogen under more mild conditions, since a local combination of the N−H δ+ ···H δ-−B dihydrogen bonds will be achieved in these materials upon heating.…”

Section: Introductionmentioning

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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Thermodynamic destabilization and reaction kinetics in light metal hydride systems

Cited by 146 publications

References 20 publications

Combined x-ray photoelectron spectroscopy and scanning electron microscopy studies of the LiBH4–MgH2 reactive hydride composite with and without a Ti-based additive

Combined x-ray photoelectron spectroscopy and scanning electron microscopy studies of the LiBH4–MgH2 reactive hydride composite with and without a Ti-based additive

Functional Materials for Sustainable Energy Technologies: Four Case Studies

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

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