Nickel macrocycles with complex hydrides—new avenues for hydrogen storage research

2010 ◽  
Vol 3 (12) ◽  
pp. 1973 ◽  
Author(s):  
Andrew James Churchard ◽  
Michał Ksawery Cyranski ◽  
Łukasz Dobrzycki ◽  
Armand Budzianowski ◽  
Wojciech Grochala
Keyword(s):  
Hydrogen Storage ◽  
Complex Hydrides

Structural Characterization of Mg2CoH5-based Nanocomposites for Hydrogen Storage

2014 ◽  
Vol 70 (a1) ◽  
pp. C741-C741
Author(s):  
Daniel Leiva ◽  
Santiago Figueroa ◽  
Bárbara Terra ◽  
Guilherme Zepon ◽  
Diego Lamas ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Structural Characterization ◽  
High Capacity ◽  
Nanocrystalline Structure ◽  
Hydrogen Desorption ◽  
Planetary Mill ◽  
Processing Route ◽  
Desorption Kinetics ◽  
Complex Hydrides

Hydrogen is considered the ideal energy carrier, mainly due to its heating power, the highest among all chemical fuels, and to possibility of using it in fuel cells, therefore with efficiency and producing only water as by-product. However, the development of safe and effective hydrogen storage solutions remains as a challenge of applied research. MgH2, Mg2FeH6 and Mg2CoH5complex hydrides are promising materials for hydrogen storage, avoiding the inconvenient of gaseous or liquid storage alternatives. The main attractives of these phases are their volumetric and gravimetric hydrogen capacities, their reversibility during absorption/desorption cycles and the relatively low cost. Recently, we have achieved an important control of the synthesis of Mg-based complex hydrides with nanocrystalline structure, using reactive milling (RM) under hydrogen atmosphere as processing route [1, 2]. In this study, we present new results concerning the synthesis, hydrogen storage properties and structural characterization of MgH2–Mg2CoH5nanocomposites prepared by RM. The nanocomposites were produced by milling different Mg-Co starting compositions (2:1, 3:1, 5:1, 7:1, 1:0) for 12 h in a planetary mill under 3 MPa of H2. All samples were fully hydrogenated during milling, generating different MgH2–Mg2CoH5hydride mixtures. Mg presents the tendency of agglomerate during milling, so the sample that presents more MgH2shows larger agglomerates. This behavior causes a slight increase in the temperature of hydrogen desorption and the presence of two peaks, showed by DSC analysis for those samples which presents MgH2and Mg2CoH5. Using in-situ XRD and XANES during hydrogen desorption revealed that Mg and Co tend to remain coupled forming intermetallics after the complex hydride decomposition, differently from that was observed for Mg2FeH6. This effect is correlated to the high-reversibility exhibited by the Mg2CoH5phase. Furthermore, the nanocomposites of MgH2+Mg2CoH5showed better H-absorption/desorption kinetics than the Mg2CoH5or MgH2alone, as shown by volumetric measurements. The combination of MgH2and Mg2CoH5is therefore a promising strategy to produce hydrogen storage materials, matching the good reversibility and high capacity of magnesium hydride with the lower thermal stability.

Materials for Hydrogen Storage: From Complex Hydrides to Functionalized Nanostructures

2011 ◽  
Author(s):  
G. P. Das ◽  
Alka B. Garg ◽  
R. Mittal ◽  
R. Mukhopadhyay
Keyword(s):  
Hydrogen Storage ◽  
Complex Hydrides

Metal-Complex Hydrides for Hydrogen-Storage Application

2005 ◽  
Vol 475-479 ◽  
pp. 2437-2440
Author(s):  
Xing Long Gou ◽  
Li Na Xu ◽  
Wei Yang Li ◽  
Jun Chen ◽  
Qiang Xu
Keyword(s):  
Hydrogen Storage ◽  
Metal Complex ◽  
Photoelectron Spectroscopy ◽  
Catalytic Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complex Hydrides ◽  
Transmission Electron ◽  
Dehydrogenation Kinetics ◽  
Transfer State

Metal-complex hydrides Li3AlH6 and V-doped Li3AlH6 nanoparticles were synthesized by solid reactions of LiH and LiAlH4 in the absence and in the presence of VCl3, respectively. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer- Emmett-Teller sorption, thermogravimetry and differential thermal analysis have been used to investigate the phase composition, microstructure and surface properties. Not only the nanocrystalline Li3AlH6, but also the coexisting catalyst with “valence-transfer” state can influence the dehydrogenation kinetics. The extension of the catalytic mechanism is attractive for reversible hydrogen storage of the alanate system.

Recent Advances in Lithium-Based Complex Hydrides for Solid-State Hydrogen Storage

2005 ◽  
Vol 475-479 ◽  
pp. 2431-2436
Author(s):  
Yuko Nakamori ◽  
G. Kitahara ◽  
T. Kudo ◽  
T. Yamagishi ◽  
Shinichi Orimo
Keyword(s):  
Solid State ◽  
Hydrogen Storage ◽  
Raman Spectra ◽  
Hydrogen Desorption ◽  
Cation Substitution ◽  
Hydrogen Storage Materials ◽  
Melting Temperatures ◽  
Desorption Temperature ◽  
Complex Hydrides ◽  
Cation Substitutions

Fundamental researches on complex hydrides are recently of great importance to develop practical hydrogen storage materials with higher gravimetric hydrogen densities than those of conventional materials. First, in this paper, we clarify the correlation between B-H atomistic vibrations in [BH4]－-anion and melting temperatures of MBH4 (M = Li, Na, and K) as indexes of hydrogen desorption temperatures. This investigation implies that partial cation substitutions using smaller sized- and/or higher valenced-cations with higher electronegativities might provide higher energy modes of Raman spectra, and then, lower hydrogen desorption temperatures. Next, as an example, LiNH2 and its partial cation substitution materials are examined. At the start of the reaction, the hydrogen desorption temperature for LiNH2 with partial cation substitution drastically decreased, with the increase in Mg concentration, to around 370K for the sample with x = 30.

scholarly journals Thermodynamic Database for Hydrogen Storage Materials

2010 ◽  
Vol 72 ◽  
pp. 213-218 ◽  
Author(s):  
Marcello Baricco ◽  
Mauro Palumbo ◽  
Eugenio Pinatel ◽  
Marta Corno ◽  
Piero Ugliengo
Keyword(s):  
Thermodynamic Properties ◽  
Hydrogen Storage ◽  
Thermodynamic Stability ◽  
Thermodynamic Database ◽  
Calphad Approach ◽  
Complex Hydrides ◽  
Crystal Code ◽  
Hydrogen Substitution ◽  
Synthesis Reactions ◽  
Energy Of Formation

In order to be used for applications, the thermodynamic stability of a candidate hydrogen storage material should be suitable for hydrogen sorption at room conditions. By mixing different hydrides, it is possible to promote the hydrogenation/dehydrogenation processes. On the other hand, small changes in composition allow a tailoring of thermodynamic stability of hydrides. Knowledge of thermodynamic stability of hydrides is thus fundamental to study the hydrogenation/dehydrogenation processes and useful to rationalize synthesis reactions and to suggest possible alternative reaction routes. The purpose of this work is to develop a consistent thermodynamic database for hydrogen storage systems by the CALPHAD approach. Experimental data have been collected from the literature. When experimental measurements were scarce or completely lacking, estimations of the energy of formation of hydrides have been obtained by ab initio calculations performed with the CRYSTAL code. Several systems of interest for hydrogen storage have been investigated, including metallic hydrides (M-H) and complex hydrides. The effect on thermodynamic properties of fluorine-to-hydrogen substitution in some simple hydrides is also considered. Calculated and experimental thermodynamic properties of various hydrides have been compared and a satisfactory agreement has been achieved.

scholarly journals Complex Hydrides for Hydrogen Storage

2003 ◽  
Author(s):  
Darlene Slattery ◽  
Michael Hampton
Keyword(s):  
Hydrogen Storage ◽  
Complex Hydrides
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