IntechOpen

Home > Books > Hydrogen Storage

Open access

Improvement on Hydrogen Storage Properties of Complex Metal Hydride

Written By

Jianjun Liu and Wenqing Zhang

Submitted: March 28th, 2012 Published: September 5th, 2012

DOI: 10.5772/50153

Hydrogen Storage IntechOpen
Hydrogen Storage Edited by Jianjun Liu

From the Edited Volume

Hydrogen Storage

Edited by Jianjun Liu

Book Details Order Print

Chapter metrics overview

3,601 Chapter Downloads

View Full Metrics
Advertisement

1. Introduction

A large challenging of world economic development is to meet the demand of energy consumption while reducing emissions of greenhouse gases and pollutants [1-5]. Hydrogen, as an energy carrier, is widely regarded as a potential cost effective, renewable, and clean energy alternative to petroleum, especially in the transportation sector [1]. Extensive efforts are being made to develop a sustainable hydrogen economy which is involved by hydrogen production, hydrogen storage, and hydrogen fuel cell in the cyclic system of hydrogen combustion [2, 6]. One key component of realizing the hydrogen economy for transportation applications is developing highly efficient hydrogen storage systems.

Table 1 presents the current available hydrogen storage techniques. Although some basic technical means such as pressurized gas and cryogenically liquefied hydrogen in containers can be used at present, hydrogen capacity is not acceptable in practical applications-driving a car up to 300 miles on a single tank, for example. Therefore, storing hydrogen in advanced solid state materials has definite advantage with regard to a low-cost, high gravimetric and volumetric density, efficiently storing and releasing hydrogen under mild thermodynamic conditions. Over the past decades, many advanced materials such as complex metal hydrides [7, 8], metal hydrides [9], metal-organic framework (MOF) [10-12], and modified carbon nanostructures have been explored to developefficient hydrogen storage techniques [13-19], but none of them can meet all requirements [20].

Liquid HydrogenCompress HydrogenMOFNanostru-ctureMetal HydrideComplex Metal Hydride
-253oC25 oC-200 oC25oC330oC"/>185oC

Table 1.

Available hydrogen storage technologies and corresponding operating temperatures.

Complex metal hydrides (for example, NaAlH4, LiAlH4, LiBH4, Mg(BH4)2, LiNH2) are currently considered as one of the promising hydrogen storage materials mainly because they have a high hydrogen capacity and are facile to tailor structural and compositional to enhance hydrogen storage performance. The typical structure of complex metal hydrides contains cation alkali metal (Mn+) and anion hydrides (AlH4-, BH4-, NH2-) with a closed-shell electronic structure. It should be pointed out that this review focuses on Al- and B-based complex metal hydrides. The bonding characteristics of these complex metal hydrides determine that their dehydriding and hydriding are unfavorable either thermodynamically or kinetically under moderate conditions. As a result, a large obstacle to use complex metal hydrides as on-board hydrogen storage materials is a relatively high hydrogen desorption temperature, a low kinetic rate for hydrogen desorption and adsorption, and a poor reversibility. It is very important to develop the effective chemical and physical methods to improve hydrogen storage properties of these materials.

Herein, take Mg(BH4)2 as an example. A possible hydrogen desorption process from Mg(BH4)2 to MgB2 are depicted by the following equations (1)-(3)[21]:

6Mg(BH4)2 5MgH2 +MgB12H12 + 13H2E1
5MgH2 5Mg +5H2E2
5Mg+ MgB12H12 6MgB2 + 6H2E3

In fact, hydrogen desorption of Mg(BH4)2 experiences a complicated hydrogen desorption process involving chemical reactions and physical changes such as mass transport and phase separation. Two thermodynamically stable intermediates, Mg(B12H12) and MgH2, are formed in the first step (Equation (1)) with enthalpy and entropy of 39 kJ/molH2 [22]. In 2008, a different value of 57 kJ/molH2 was obtained [23]. The hydrogen desorption reactions ofequations (2) and (3) have endothermicity of 75 and 87 kJ/molH2. Therefore, the equations (2) and (3) only occur at a high temperature, 572K of equation (2) and 643 K of equation (3)[24]. In addition, a stable intermediate usually leads to a thermodynamic pitfall which trap a large amount of hydrogencannot be cycled. Very recently, Jensen et al. found that at a high condition (~400oC and ~950bar), equations (2)-(3) also can participate hydrogen release/uptake reactions [25]. However, these conditions are unfeasible for practical application.

Promoting the kinetic rates of hydrogen desorption and adsorption of complex metal hydrides play an important role in developing hydrogen storage material. However, because the bonds BH in BH4-and AlH in AlH4-are relatively strong, their dissociations require overcoming a high barrier. Additionally, two processes must be considered to enhance the kinetic rate of hydrogen desorption and adsorption. Firstly, phase transitions coupled with chemical reactions, which sometimes experience a high barrier, slow down the kinetic rate. Secondly, hydrogen diffusion is also important factor to take effect on the kinetic rate of hydrogen desorption and adsorption.

In 1997, Bogdanović et al. demonstrated that a small amount of Ti-compounds doped in NaAlH4 can enhance the kinetic rates of both hydrogen desorption and adsorption of NaAlH4, reduce hydrogen desorption temperature from 210 to 120oC and hydrogen adsorption pressure from 350 to 100 bar, as well as have a good reversibility (80% H) [26]. It stimulated the extensive studies in theory [27-41] and experiment [42-54] to improve the kinetic and thermodynamic properties of hydrogen desorption and adsorption of complex metal hydrides in order to develop the practical hydrogen storage material. More importantly, these studies have extended from doping transition metal to chemical and physical methods such as nanoengineering, and cation substitution. These structural and composition tailor are expected to have strong effects on the thermodynamics of the complex hydrides and the kinetics of hydrogen release and uptake from either the bulk crystalline phase or nanosized particles.

In the past years, there are a few reviews to discuss hydrogen storage materials with different points of view. In this chapter, we focus on improvement on hydrogen storage properties of complex metal hydrides, that is, tailoring thermodynamics and kinetic properties of their hydrogen desorption and adsorption by the various techniques. We do not intend to provide a complete review of the literature about this topic, but rather to emphasize tailoring effect on hydrogen storage properties of complex metal hydrides. The research is mainly categorized into three parts: (i) doping transition metal; (ii) nanoengieering techniques; and (iii)cation Substitution.Finally, we present a conclusive remark for developing complex metal hydrides as hydrogen storage materials by means of altering thermodynamic and kinetic properties.

Advertisement

2. Improving hydrogen storage properties

2.1. Doping transition metal

Catalysts have been widely exploited to hydrogen storage materials to improve the kinetic and thermodynamic properties of hydrogen desorption and adsorption in complex metal hydrides and metal hydrides, following the pioneering work of Bogdanović and Schwickardi [26, 55]. They demonstrated that doping the complex metal hydrides NaAlH4 with a few mol% of Ti lowered the decomposition temperature, improving the kinetics, and, importantly allowed rehydrogenation of the decomposition products. This finding quickly sparks worldwide research activities that aimed at developing catalytically enhanced NaAlH4 and related complex metal hydrides as practical hydrogen storage medium. Then, a great number of experimental and theoretical studies have been devoted to characterize the structures and effect of Ti in NaAlH4. Although many models were proposed to describe (de)hydrogenation of Ti-doped NaAlH4, no clear consensus about structures and catalytic mechanism of Ti in NaAlH4 has been achieved. The only established fact from these studies is a surface-localized species containing a nascent binary phase Ti-Al alloy formed during cyclic dehydriding and rehydriding processes [28, 43, 51, 56-58].

Many experimental studies about the local structure of Ti-doped NaAlH4 showed that highly dispersed Ti in the Al surface plays an important role in hydrogen uptake and release processes. As shown in Figure 1, TiAl3 alloy is the most likely form after dehydriding Ti-doped NaAlH4 [43, 59]. It is consistent with what TiAl3 is thermodynamically the most stable stability in Ti-Al system. The local structure of active species has TiAl and TiTi bond distance of 2.79 and 3.88Å, respectively. After mechanical milling, TiCl3 is reduced to zero-state Ti by interaction with NaAlH4.However, TiAl3 doped in NaAlH4 were found to be substantially less effective than TiCl3. Therefore, the catalytic activity of Ti structure may be summarized as "Ti in the Al surface > TiAl3 cluster > crystalline TiAl3" [50].

In fact, determining accurately the local structures in such a complicated system including a dynamic hydriding/dehydriding processes is extremely challenging to many experimental techniques. In this aspect, DFT-based first-principles methods have shown their advantages. Several theoretical studies have been performed with emphasis on substitution of Ti for Al and Na atoms in Ti-doped NaAlH4 bulk and surfaces.Substitution of Ti for Al has been shown theoretically to be the preferred location in bulk NaAlH4. Ĩňiguez et al. studied the structure, energetics, and dynamics of pure and Ti-doped NaAlH4, focusing on the possibility of substitutional Ti doping in the bulk. They found that that the doped Ti prefers to substitute for Na and further attract surrounding hydrogen atoms, softening and/or breaking the Al-H bonds. The same group of authors extended their studies to determine the location of Ti. These later results showed that Ti prefers to be on the surface, substituting for Na, and attracting a large number of H atoms to its vicinity. They predicted that a TiAln(n>1) structure may be formed on the surface of the sodium alanate [30]. However, Løvvik et al. also suggested that substitution of Ti in bulk NaAlH4 is less favorable than that near surface or defect positions. On the NaAlH4 (001) surface, DFT calculations by Yildirim and Iňiguez showed substitution of Ti for Na is the preferred site [60] whereas Løvvik and Opalka found substitution of Ti for Al is more favorable [40]. The difference has been attributed to the different reference states used in energy calculations.

Figure 1.

Normaalized XANES spectra for Ti-doped NaAlH4 and the reference compounds (left);X-ray diffraction indicating TiAl3 production in the NaAlH4 system when mechanically milled in a 3:1 ratio with TiCl3. Reproduced from [43] for (left) by permission ofThe Royal Society of Chemistry, and from [59] for (right) by permission of Elsevier.

However we approached this problem based on a surface model and found a different structure and mechanism. The TiAl3H12 local structure was identified in Ti-doped NaAlH4 (001) and (100) surfaces [41]. Our calculated results show that the hydrogen desorption energies from many positions of TiAl3Hx are reduced considerably as compared with that from the corresponding clean, undoped NaAlH4 surfaces. Furthermore, we showed that the TiAl3H12 complex has an extended effect beyond locally reducing the hydrogen desorption energy. It also facilitates hydrogen desorption at a reduced desorption energy by either transferring the hydrogen to TiAl3Hx or by reducing the hydrogen desorption energy in neighboring AlH4- by linking these AlH4- units with the complex structure. Our predicted interstitial TiAl3Hx structure was supported by a recent combined Ti K-edge EXAFS, Ti K-edge XANES, and XRD study of TiCl3-doped NaAlH4 by Baldé et. al [61]. These authors observed that the interstitial structure accounts for more than 70% of all Ti doped in NaAlH4.

Extensive experimental studies have demonstrated that transition metals(TM) can accelerate the kinetic rate of hydrogenation and dehydrogenation reactions in this system. In terms of chemical reactions, TM can weaken AlH and HH bonds and thus reduce transition state barriers of hydrogen reactions through electron backdonation interaction from d orbital of TM to σ* of these bonds [33]. In addition, addition of TM also leads to formation of defect which is also favorable to kinetic improvement of hydrogen diffusion in solid-state materials [31, 62].

Figure 2.

DFT-GGA relaxed structure of Ti-doped NaAlH4(001) with Ti in the surface interstitial site. (b) Detailed local structure of the TiAl3H12 complex shown in (a). Reprinted from [41].

Few experimental studies on tailoring thermodynamic properties of NaAlH4 by doping TM were performed. Bogdanović and Schüth performed pressure-concentration isotherms for hydrogen desorption of NaAlH4 with different doping levels of Ti [63]. They found Ti doping can significantly alters the thermodynamics of the system, which is demonstrated by the change of the dissociation pressure with doping level. Such a thermodynamic change is mainly attributed to Ti-Al alloy formation.

As mentioned previously, our studies for Ti-doped NaAlH4 found that TiAl3Hx structure has a significantly effect to reducing hydrogen desorption energy [41, 64]. Such a thermodynamic tuning effect can be explained by the closed-shell 18-electron rule of transition metal structures. In addition, Mainardi et al. performed electronic structure calculations and molecular dynamic simulations for kinetics of hydrogen desorption of NaAlH4 [65]. They found that the rate-determining step for hydrogen desorption was hydrogen evolution from associated AlH4 species. Ti is predicted to stay on the hydride surface and serves as both the catalytic species in splitting hydrogen from AlH4-/AlH3 groups as well as the initiator Al nucleation sites in Ti-doped NaAlH4 system.

In terms of NaAlH4, an important issue is to select high efficient catalyst for improving thermodynamic and kinetic properties of hydrogenation and dehydrogenation. Anton and Bogdanović studied the hydrogen desorption kinetics of NaAlH4 by different transition metals(TM) and found early TMs have a better catalytic effect for hydrogen desorption kinetics than later TMs [66, 67]. In 2008, we performed DFT calculations for hydrogen desorption mechanism of 3d TM-doped NaAlH4. Similarly, TMAl3Hx were determined to the most stable structures [33]. In these structures, the electron transfer between hydrogen and Al groups mediated by the d-orbtials of TMs plays an important role in hydrogen release/uptake from analate-based materials.

Only a few publications focus on the theoretical exploration for the mechanism of Ti-catalyzed hydrogenation process [28, 29, 68]. In fact, Ti-catalyzed hydrogenation process includes hydrogen dissociation and the subsequent formation of any hydrogen-containing mobile species from Ti active sites. In 2005, Chaudhuri et. al performed DFT calculations to investigate the position and catalytic mechanism for hydrogenation of Ti in Al (001) surface structure [29]. Two next-nearest-neighbor Ti atoms located on the top of 22 Al(001) surface are more favorable to hydrogen dissociation than others positions such as two nearest-neighbor. In this particular local arrangement, the HH bond can be automatically broken and the dissociated H atoms are connected with Ti and Al. The analysis of electronic structure showed that the bond-breaking process is enhanced by electron backdonation from Ti-3d orbitals to hydrogen * orbitals. However, Ti was believed to promote formation of AlH3 or NaH vacancies but not included explicitly in the model. Furthermore, NaH was not treated explicitly as the study focused n dehydrogenation. Therefore, a system directly involving NaH is necessary to account for its role in the cyclic process of using NaAlH4 as a hydrogen storage medium.

Recently, we studied hydrogen adsorption process of TiAl3Hx supported on the NaH(001) surface in order to understand hydrogenation mechanism of Ti-doped NaH/Al [69]. Our results support that TiAl3Hx gains electronic charge from the NaH hydrides. The hydrided TiAl3Hx cluster on the NaH surface which dissociates the H2 molecule at the Ti site in contact with the surface. Furthermore, our DFT-based molecular dynamics simulation (Figure 3) demonstrated that TiAl3Hx clusters are active for H2 dissociation after acquiring electronsfrom the hydride of NaH surface.

Another complex hydride similar to NaAlH4 but having an even higher intrinsic hydrogen capacity is LiAlH4. The decomposition of LiAlH4 is believed to undergo similar steps to NaAlH4. The first decomposition step from tetrahedral LiAlH4 to octahedral Li3AlH6 is weakly endothermic [70, 71]. The second decomposition reaction from octahedral Li3AlH6 to LiH and Al phase was found to be endothermic with ΔH of 25 kJ/molH2. Its dehydriding was observed to occur at 228-282 °C, likely due to kinetic limiting steps. Apparently, the decomposition temperature is too high for practical purposes. The decomposition of LiAlH4 is very slow without a catalyst [72-75].

Balema et al. found that the mixture of 3 mol% TiCl4 and LiAlH4 under ball milling can cause LiAlH4 to rapidly transform into Li3AlH6 [72, 73].In 2010, Langmi et al. found that TiCl3 can enhance thermodynamic properties to reduce hydrogen desorption temperature from ~170oC for the first step while melting and 225oC for the second step to 60-75oC below the melting point [76]. These studies indicated that doping TiCl3 can improve thermodynamic and kinetic properties of (de)hydrogenation processes of LiAlH4.

Figure 3.

Snapshots from ab initio molecular dynamics trajectories for H2 dissociation on TiAl3 and TiAl3H4 clusters supported on NaH (001) surface. Purple, white, pink, gray, and green balls represent Na, H, Al, and Ti, and dissociating H2. Reprinted from [69] by American Chemical Society.

Very recently, Liu et al. directly synthesized LiAlH4 from commercially available LiH and Al powders in the presence of TiCl3 and Me2O for the first time [77]. However, without TiCl3 or adding metallic Ti, LiAlH4 is not observed in experiment. It suggests that with the presence of TiCl3, LiAlH4 can be cycled, making it a reversible hydrogen storage material. However, thecatalytic effect of TiCl3 for enhancing thermodynamic and kinetic properties of LiH+Al+3/2H2LiAlH4 still is not studied so far.

Complex metal borohydrides have attracted extensive attention due to due to its intrinsically high gravimetric and volumetric hydrogen capacities (for example, LiBH4, 18.2 wt%, 121 kg/m3). Unfortunately, the B-H bond in pure LiBH4 material is extremely strong and only liberates 2% hydrogen around the melting point (541-559 K) [1]. Starting from LiBH4, the partial decomposition to LiH(s)+B(s)+3/2H2(g) has the standard enthalpy of 100.3 kJ/molH2 [78]. The highly endothermic decomposition reaction indicates hydrogen release from LiBH4 must occur at elevated temperatures. The experimental results of Züttel et. al showed that a significant hydrogen desorption peak started at 673 K and reached its maximum value around 773 K [79, 80]. In 2007, Au et al. showed that LiBH4 modified by metal oxides or metal chlorides, such as TiO2 and TiCl3, could reduce the dehydrogenation temperature and achieve re-hydrogenation under moderate conditions [81, 82]. Modified LiBH4 releases 9 wt% H2, starting as low as 473 K, which is significantly lower than the hydrogen releasing temperature of 673 K for pure LiBH4. After being dehydrogenated, the modified LiBH4 can absorb 7~9 wt% H2 at 873 K and 70 bar, a significant improvement from 923 K and 150 bar for pure LiBH4 [80]. Very recently, Fang, et al. reported that a mechanically milled 3LiBH4/TiF3 mixture released 5-6 wt% hydrogen at temperatures of 343~363 K [83]. Similarly, other dopants have been attempted to reduce the hydrogen desorption temperature of MgH2. Clearly, addition of Ti-compounds (TiO2, TiCl3, and TiF3) result in a strong improvement for hydrogen desorption and, to a lesser extent, for re-hydrogenation. On the other hand, the improvement brought by these additives to LiBH4 is not sufficient to make LiBH4 viable as a practical hydrogen storage media

In 2009, we presented our DFT calculations for structures and hydrogen desorption Ti-doped LiBH4 surface [84]. Molecular orbital analysis showed that the structural stability could be attributed to the symmetry-adapted orbital overlap between Ti and "inside" BH bonds. Several surfaces (001) and (010) can desorb hydrogen in molecular form by high spin state (triplet), while surface (100) must first desorb hydrogen atoms, followed by the formation of a hydrogen molecule in the gas phase.

Mg(BH4)2 is considered as another promising hydrogen storage materials and it releases approximately 14.9 wt% of hydrogen when heated up to 870K [22, 23, 85-93]. As discussed in Introduction, the dehydrogen process is found to go through multiple steps with formation of some stable intermediates such as MgB12H12 and MgH2 [21]. Therefore, it is very necessary to tune thermodynamic and kinetic properties of hydrogenation and dehydrogenation of Mg(BH4)2. The addition of TiCl3 into Mg(BH4)2 was demonstrated to be effective on tuning thermodynamic properties [86]. Hydrogen desorption temperature is reduced to from 870 K to 361 K. However, Ti species gradually convert to Ti2O3 and TiB2 during cycling experiments of hydrogen desorption/adsorption [94], though the catalytic mechanism is still not clear.

2.2. Nanoengineering techniques

Due to size effect and morphology, nanoparticles often display some different physical and chemical properties compared to bulk particles and are applied for instance in catalysis, chemical sensors, or optics [95-98]. A small size of particle can decrease hydrogen diffusion lengths and increase surface interaction with H2. More importantly, thermodynamics of hydrogen desorption/adsorption of complex metal hydrides usually can be adjusted by controlling particle size [34, 99-103].Particle size of complex metal hydrides can be usually reduced to ~200 nm by ball milling technique, for NaAlH4 preferably in the presence of TM-based catalysts [57, 104, 105]. Obtaining smaller certain sizes of particles of complex metal hydrides is still challenging. Moreover, with the method of ball milling, the particle size is very difficult to control in an exact value and the size distribution is broad.

In the recent years, a new technique, nanoscaffold, has been extensively used to produce a different size of nanoparticles of complex metal hydrides.However, it should be pointed out that development of controlling nanosize of particle by nanoscaffold technique is really dependent on preparation of porous nanomaterials. Additionally, it is understood that a nanoscaffold technique unavoidably results in a low hydrogen capacity of complex metal hydrides.

By this technique, Baldé et al. synthesized a nanofiber-supported NaAlH4 with discrete particle size ranges of 1-10μm, 19-30nm, and 2-10nm [99]. The experimental measurement on temperature programmed desorption of H2 for NaAlH4 nanoparticles was presented in Figure 4. The hydrogen desorption temperatures are decreased from 186oC of 1-10μm to 70oC of 2-10nm. More importantly, the activation barriers of hydrogen desorption also change from 116 to 58 kJ/mol correspondingly. It suggests that size reduction of nanoparticle can tailor thermodynamic and kinetic properties of hydrogen desorption/adsorption process of NaAlH4. In addition, they also reported that decreasing particle sizes also lowered the pressures needed for hydrogen uptake. In 2010, Gao et al. confined NaAlH4 into 2-3 nm nanoporous carbon [102]. They observed that H2 release temperature and rehydrogenation conditions were significantly improved. More importantly, the total reaction is changed to a single step reaction without Na3AlH6 formed. The similar studies also exhibited nanosize effect on tuning thermodynamic and kinetic properties for complex metal hydrides.

In 2011, Majzoub et al. presented first-principles calculations for phase diagram of small cluster of Na-Al-H system [34]. They found that decreasing cluster size not only reduces hydrogen desorption temperature but also change reaction path from NaAlH4Na3AlH6+Al+H2NaH+Al+H2 in bulk structure to NaAlH4 NaH+Al+H2 in a small size of nanoparticles. It should be attributed to the instability of Na3AlH6 nanoparticle with a small size. All these studies indicate that controlling nanostructure size provides a practical avenue to tailor thermodynamic and kinetic properties of (de)hydrogenation of complex metal hydrides.

Figure 4.

Temperature programmed desorption profile of H2 for NaAlH4 supported on carbon nanofiber. Reproduced from [99] by permission of American Chemical Society (copyright 2008).

Similarly, decreasing particle size by nanoscaffold technique has also been extended to LiBH4. Vajo and Wang filled LiBH4 into carbon aerogel and AC carbon to form different nanoparitcles [106-108]. They found hydrogen desorption temperature was reduced and kinetic rate was significantly enhanced. Unfortunately, nanosize effect of hydrogen desorption and adsorption of LiBH4 is still not reported so far.

In sum, a small size of nanoparticle of complex metal hydrides can directly result in the change of thermodynamic and kinetic properties for hydrogen adsorption/desorption processes. However, there are two very important questions on nanosize effect of particles of complex metal hydrides. One is to determine the correlation of tuning thermodynamic and kinetic properties with particle size. The other is to establish the hydrogen desorption/adsorption mechanism of complex metal hydrides in a different nanosize.

Except for size effect, nanoengieering also involves the composition of complex metal hydride and nanostructures. Berseth et al. performed joint experimental and theoretical studies for hydrogen uptake and release of NaAlH4 attached on carbon nanostructures such as C60, graphene, and nanotubes [15]. Figure 5 displayed the correlation of hydrogen desorption energies of NaAlH4 with electron affinities of carbon nanostructures. It suggests that that the stability of NaAlH4 originates with the charge transfer from Na to the AlH4 moiety, resulting in an ionic bond between Na+ and AlH4- and a covalent bond between Al and H. Interaction of NaAlH4 with an electronegative substrate such as carbon fullerene or nanotube affects the ability of Na to donate its charge to AlH4, consequently weakening the AlH bond and causing hydrogen to desorb at lower temperatures aswell as facilitating the absorption of H2 to reverse the dehydrogenation reaction.

Similarly, Wellons et al. showed that the addition of carbon nanostructure C60 to LiBH4 has a remarkable catalytic effect, enhancing the uptake and release of hydrogen [109]. A fullerene-LiBH4 composite demonstrates catalytic properties with not only lowered hydrogen desorption temperatures but also regenerative rehydrogenation at a relatively low temperature of 350oC. This catalytic effect is probably attributedto C60 interfering with the charge transfer from Li to the BH4moiety, resulting in a minimized ionic bond between Li+ and BH4-, and a weakened BH covalent bond. Interaction of LiBH4 with an electronegative substrate such as carbon fullerene affects the ability of Li to donate its charge to BH4, consequently weakening the BH bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H2.

Figure 5.

Correlation of the carbon substrate electron affinity and the hydrogen removal energy. Reprinted from [15] by permission of American Chemical Society (copyright 2009).

2.3. Cation substitution

In terms of complex metal hydrides, their stability really depends upon electronic affinity of metal atom. The lower the electronic affinity of metal is, the less stable hydride is. It can further be explained by transferred electron amount from metal atom to hydride. Løvvik, Jensen, Ormio, and Miwa et al. proposed that the metal element with a large electronic affinity can be used to substitute the original metal in order to destabilize reactants, making the enthalpy of the hydrogen release reaction favorable [110-117].

The two cations mixed in one hydride are expected to function synergistically to maintain reasonable stability, and at the same time provide a favorable decomposition enthalpy. Sorby et al. performed an experimental study about dual cation aluminium hydride, K2Na(AlH4)3 [118]. Because K has a smaller electron affinity, K2Na(AlH4)3 was measured to have a higher hydrogen desorption temperature up to 285oC, which is well consistent with theoretical predict.

Extensive DFT calculations showed that bialkali hexahydrides, such as K2LiAlH6, K2NaAlH6, KNa2AlH6, and LiNa2AlH6, are stable compared to the pure alanates [110, 111]. In fact, LiNa2AlH6 has been synthesized experimentally [112, 113]. Mixed aluminohydrides such as LiMg(AlH4)3 and LiMgAlH6 have also been predicted based on DFT studies and have been synthesized and characterized experimentally [119, 120]. Although their overall hydrogen storage performance was not fully examined, some of these compounds exhibit favorable decomposition temperatures.

Many theoretical and experimental studies on cation modification have been performed to improve thermodynamics and kinetics for borohydrides. Au et al. synthesized a series of bimetallic M1M2(BH4)n (M1, M2=Li, Mg, and Ti) and experimentally measured their hydrogen desorption temperature and hydrogen capacity [121]. They found that dehydrogenation temperature was reduced considerably and the dehydrided bimetallic borohydrides reabsorbed some of hydrogen released, but the full rehydrogenation is still very difficult. In 2010, Fang et al. studied formation of decomposition of dual-cation LiCa(BH4)3 using X-ray diffraction and thermogravimetry/differential scanning calorimetry/mass spectroscopy techniques [122]. It was found that LiCa(BH4)3 exhibits improved (de)hydrogenation properties relative to the component phases. In 2011, Jiang et al studied synthesis and hydrogenstorage properties of Li-Ca-B-H hydride [123]. They found that the first dehydrogenation temperature is about 70oC, much lower than the pristine LiBH4 and Ca(BH4)2. All these studies indicate that dual-cation borohydrides have a better thermodynamic property for hydrogen desorption than the single cation borohydride. Therefore, dehydrogenation temperature is significantly improved relative to the single phase.

In addition, some experimental studies on multivalent cation borhydrides such as Al, Sc, and Ti were carried out to reduce hydrogen desorption temperature [115, 117, 124-132]. However, theoretical studies on dehydrogenation mechanism including intermediates and products are desired for further improvement. However, extensive DFT computations have been performed to assess a large number of possible destabilized metal hydrides [133-137]. By assessing the enthalpies of all possible reactions, more than 300 destabilization reactions were predicted to have favorable reaction enthalpies [133]. Wolverton et al. proposed several guidelines to destabilize thermodynamically the metal hydrides in order to design novel hydrogen storage materials [138]. Basically, the enthalpy of the proposed destabilized reaction must be less than the decomposition enthalpies of the individual reactant phases. In addition, if the proposed reaction involves a reactant that can absorb hydrogen, the formation enthalpy of the corresponding hydride cannot be greater in magnitude than the enthalpy of the destabilized reaction.

Vajo et al. examined this strategy by altering the thermodynamics and kinetics of (de)hydrogenation of several metal hydrides [139]. The equilibrium hydrogen pressure and reaction enthalpies can be changed with additives that form new alloys or compound phases upon dehydriding. The formation of new phases lowers the energy of dehydrided state and efficiently destabilizes the component hydrides. A series of experimental explorations have been performed to destabilize the reaction products of LiBH4 and successfully reduce the dehydriding temperatures [139-141].

Advertisement

3. Conclusive remarks

Complex metal hydrides with a high hydrogencapacity have been considered as potential candidates for on-board hydrogen storage materials. However, the high hydrogen desorption temperature and sluggish kinetics prevent them from being applied in practice. It is attributed to unfavorable thermodynamic and kinetic properties of (de)hydrogenation. Over a past decade, a number of efforts have been devoted to improve hydrogen storage properties by altering thermodynamic and kinetic properties of (de)hydrogenation. Doping transition metal in complex metal hydrides can be regarded as a very effective means to tailor thermodynamics and promote kinetics. However, the catalytic mechanism of TM doped in hydrides remains unconfirmed because (de)hydrogenation includes complicated physical and chemical processes. TM may exhibit different structures and catalytic mechanisms in each step. Nanoengineering has extensively been applied to improve thermodynamic and kinetic properties of hydrogen storage materials by means of reducing particle size or mixing with nanostructures. However, some catalytic effect is restricted from some properties such as certain size, as well as chemical and physical properties of nanostructures. Cation substitution to form dual-cation hydride is generally used as a technique to alter thermodynamic property. Although this modification is effective to destabilize reactant, the modified crystal structure does not maintain during reversible processes of (de)hydrogenation.

Advertisement

Acknowledgement

Jianjun Liu acknowledge support by the startup funding by Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS).

References

  1. 1. SchlapbachL.ZüttelA.Hydrogen-storage materials for mobile applications. Nature. 20014143538
  2. 2. Crabtree GW, Dresselhaus MS, Buchanan MV. The hydrogen economy. Physics Today.2004Dec;57123944
  3. 3. SchultzM. G.DiehlT.BrasseurG. P.ZittelW.Air pollution and climate-forcing impacts of a global hydrogen economy. Science. 2003Oct 24;30256456247
  4. 4. SchüthF.Challenges in hydrogen storage. European Physical Journal-Special Topics. 2009Sep;17615566
  5. 5. Dresselhaus MS, Thomas IL. Alternative energy technologies.Nature. 20014143327
  6. 6. OhiJ.Hydrogenenergy.cycleAn.overviewJ.MaterRes.2005Dec;201231807
  7. 7. OrimoS.NakamuraY.EliseoJ. R.ZüttelaA.JensenC. M.Complex Hydrides for Hydrogen Storage. Chem Rev. 200710710411132
  8. 8. JainI. P.JainP.JainA.Novel hydrogen storage materials: A review of lightweight complex hydrides. J Alloys Compd. 2010Aug 6;503230339
  9. 9. GraetzJ.New approaches to hydrogen storage. Chem Soc Rev. 2009387382
  10. 10. Rowsell JLC, Yaghi OM.Strategies for Hydrogen Storage in Metal-Organic Frameworks. Angew Chem Int Ed. 20054446709
  11. 11. El -KaderiH. M.HuntJ. R.Mendoza-CortesJ. L.CoteA. P.TaylorR. E.O’KeeffeM.et al.Designed Synthesis of 3D Covalent Organic Frameworks. Science. 200731626872
  12. 12. RosiN. L.EckertJ.EddaoudiM.VodakD. T.KimJ.O’KeeffeM.et al.Hydrogen Storage in Microporous Metal-Organic Frameworks. Science. 200330011279
  13. 13. NiemannM. U.SrinivasanS. S.PhaniA. R.KumarA.GoswamiD. Y.StefanakosE. K.Nanomaterials for Hydrogen Storage Applications: A Review. J Nanomater. 2008
  14. 14. ZhaoY.KimY.DillonA. C.MJHebenZhang. S. B.Hydrogen Storage in Novel Organometallic Buckyballs. Phys Rev Lett. 2005155504 EOF
  15. 15. BersethP. A.HarterA. G.ZidanR.BlomquistA.AraujoC. M.ScheicherR. H.et al.Carbon Nanomaterials as Catalysts for Hydrogen Uptake and Release in NaAlH4. Nano Lett. 20099415015
  16. 16. LiM.LiY.ZhouZ.ShenP.ChenZ.CaCa-Coated Boron Fullerenes and Nanotubes as Superior Hydrogen Storage Materials. Nano Lett. 2009919448
  17. 17. YoonM.YangS.WangE. G.ZhangZ.Charged Fullerenes as High-Capacity Hydrogen Storage Media. Nano Lett. 20079257883
  18. 18. YildirimT.CiraciS.TitaniumTitanium-Decorated Carbon Nanotubes as a potential high-capacity hydrogen storage medium. Phys Rev Lett. 2005175501 EOF
  19. 19. YoonM.YangS.KickeC.WangE. G.GeoheganD.ZhangZ.Calcium as the Superior Coating Metal in Functionalization of Carbon Fullerenes for High-Capacity Hydrogen Storage. Phys Rev Lett. 2008206806 EOF
  20. 20. FelderhoffM.WeidenthalerC.vonHelmolt. R.EberleU.Hydrogenstorage.theremaining.scientifictechnologicalchallenges.Phys Chem ChemPhys. 2007Jun 7;921264353
  21. 21. LiH. W.YanY. G.OrimoS.ZuttelA.JensenC. M.Recent Progress in Metal Borohydrides for Hydrogen Storage. Energies. 2011Jan;41185214
  22. 22. MatsunagaT.BuchterF.MauronP.BielmanA.NakamoriY.OrimoS.et al.Hydrogen storage properties of Mg(BH4)2. JAlloys Compd. 2008Jul 14;459(1-2):583-8.
  23. 23. LiH. W.KikuchiK.NakamoriY.OhbaN.MiwaK.TowataS.et al.Dehydriding and rehydriding processes of well-crystallized Mg(BH4)2 accompanying with formation of intermediate compounds. Acta Materialia. 2008Apr;56613427
  24. 24. GrochalaW.EdwardsP. P.thernal decomposition of non-interstital hydrides for storage and production of hydrogen. Chem Rev. 2004
  25. 25. SeveraG.RonnebroE.JensenC. M.Direct hydrogenation of magnesium boride to magnesium borohydride: demonstration of > 11 weight percent reversible hydrogen storage. ChemCommun. 20104634213
  26. 26. BogdanovićB.SchwickardiM.Ti-doped alkali metal aluminum hydrides as potential novel reversible hydrogen storage materials. J Alloys Compd. 1997
  27. 27. AguayoA.SinghD. J.Electronic structure of the complex hydride NaAlH4. Phys Rev B. 2004155103 EOF
  28. 28. ChaudhuriS.GraetzJ.IgnatovA.ReillyJ. J.MuckermanJ. T.Understanding the Role of Ti in Reversible Hydrogen Storage as Sodium Alanate: A Combined Experimental and Density Functional Theoretical Approach. J Am Chem Soc. 2006128351140415
  29. 29. ChaudhuriS.MuckermanJ. T.FirstFirst-Principles Study of Ti-Catalyzed Hydrogen Chemisorption on an Al Surface: ACritical First Step for Reversible Hydrogen Storage in NaAlH4. J Phys Chem B. 200510969527
  30. 30. ÍñiguezJ.YildirimT.First-principles study of Ti-doped sodium alanate surfaces. Appl Phys Lett. 2005103109 EOF
  31. 31. AraújoC. M.LiS.AhujaR.JenaP.Vacancy-mediated hydrogen desorption in NaAlH4. Phys Rev B. 2005
  32. 32. AraújoC. M.AhujaR.OsorioGuillén. J. M.JenaP.Role of titanium in hydrogen desorption in crystalline sodium alanate. Appl Phys Lett. 2005251913 EOF
  33. 33. LiuJ.HanY.GeQ.Effect of Doped Transition Metal on Reversible Hydrogen Release/Uptake from NaAlH4. Chem Eur J. 200915168595
  34. 34. MajzoubE. H.ZhouF.OzolinsV.FirstFirst-Principles Calculated Phase Diagram for Nanoclusters in the Na-Al-H System: A Single-Step Decomposition Pathway for NaAlH4. J Phys Chem C. 2011Feb 17;1156263643
  35. 35. WoodB. C.MarzariN.Dynamics and thermodynamics of a novel phase of NaAlH4. Phys Rev Lett. 2009185901 EOF
  36. 36. HuangC. K.ZhaoY. J.SunT.GuoJ.SunL. X.ZhuM.Influence of Transition Metal Additives on the Hydriding/Dehydriding Critical Point of NaAlH4. J Phys Chem C. 2009Jun 4;11322993643
  37. 37. MarashdehA.OlsenR. A.LovvikO. M.Kroes-JG.NaAl. H.Clusterwith.TwoTitanium.AtomsAdded.J. NaAlH4 Cluster with Two Titanium Atoms Added. J Phys Chem C. 2007111820613
  38. 38. VeggeT.Equilobrium Structure and Ti-catalyzed H2 desorption in NaAlH4 nanoparticles from DFT. Phys Chem Chem Phys. 20068485361
  39. 39. PelesA.ChouM. Y.Lattice dynamics and thermodynamic properties of NaAlH4: Density-functional calculations using a linear response theory. Phys Rev B. 2006May;73(18):184302.
  40. 40. Løvvik OM, Opalka SM.Density functional calculations of Ti-enhanced NaAlH4. Phys Rev B. 2005
  41. 41. LiuJ.GeQ. A.precursorstate.forformation.ofTi.Alcomplex.inreversible.hydrogendesorption/adsorption.fromTi-doped.NaAl. H.Chemical Communications. 200620061718224
  42. 42. GraetzJ.ReillyJ. J.JohnsonJ.IgnatovA. Y.TysonT. A.X-ray absorption study of Ti-activated sodium aluminum hydride. Appl Phys Lett. 20048535002
  43. 43. FelderhoffM.KlementievK.GrunertW.SpliethoffB.TescheB.Bellostavon.ColbeJ. M.et al.Combined TEM-EDX and XAFS studies of Ti-doped sodium alanate. Phys Chem Chem Phys. 2004617436974
  44. 44. ThomasG. J.GrossK. J.YangN. Y. C.JensenC.Microstructural characterization of catalyzed NaAlH4. J Alloys Compd. 2002Jan 17;3307027
  45. 45. SandrockG.GrossK. J.ThomasG.Effect of Ti-catalyst content on the reversible hydrogen storage properties of the sodium alanates. J Alloys Compd. 2002299 EOF308 EOF
  46. 46. Gross KJ, Thomas GJ, Jensen CM.Catalyzed alanates for hydrogen storage. J Alloys Compd. 2002683 EOF690 EOF
  47. 47. BrinksH. W.FossdalA.FonnelpJ. E.HaubackB. C.Crystal structure and stability of LiAlD4 with TiF3 additive. J Alloys Compd. 20053972915
  48. 48. BalemaV. P.BalemaL.Missing pieces of the puzzle or about some unresolved issues in solid state chemistry of alkali metal aluminohydrides. Phys Chem Chem Phys. 20057613104
  49. 49. BogdanovićB.FelderhoffM.PommerinA.SchuthF.SpielkampN.StarkA.Cycling properties of Sc- and Ce-doped NaAlH4 hydrogen storage materials prepared by the one-step direct synthesis method. J Alloys Compd. 20094713836
  50. 50. Baldé CP, Stil HA, van der Ederden AMJ, de Jong KP, Bitter JH.Active Ti Species in TiCl3-doped NaAlH4. Mechamism for catalyst Deactivation. J Phys Chem B. 20071112797802
  51. 51. BrinksH. W.SulicM.JensenC. M.HaubackB. C.TiCl.EnhancedNa.AlH.Impactof.ExcessAl.Developmentof.theAl1-y.TiyPhase.Jensen CM, Hauback BC. TiCl3-Enhanced NaAlH4: Impact of Excess Al and Development of the Al1-yTiy Phase. J Phys Chem B. 200611027405
  52. 52. MajzoubE. H.HerbergJ. L.StumpfR.SpanglerS.MaxwellR. S. X. R. D.investigationN. M. R.ofTi-compound.formationin.solution-dopingof.sodiumaluminum.hydridessolubility.ofTi.inNa.AlH.crystalsgrown.inT. H. F.JL, Stumpf R, Spangler S, Maxwell RS. XRD and NMR investigation of Ti-compound formation in solution-doping of sodium aluminum hydrides: solubility of Ti in NaAlH4 crystals grown in THF. J Alloys Compd. 200539426570
  53. 53. LeonA.KircherO.RosnerH.DecampsB.LeroyE.FichtnerM.etal. S. E. M.characterizationT. E. M.ofsodium.alanatedoped.withTi.Clor.smallTi.clusters.Ti13 T. H. F.J Alloys Compd. 2005
  54. 54. HerbergJL, Maxwell RS, Majzoub EH. 27Al and 1H MAS NMR and 27Al multiple quantum studies of Ti-doped NaAlH4. J Alloys Compd. 2005
  55. 55. BogdanovićB.BrandR. A.MarjanovicA.SchwickardiM.TolleJ.Metal-doped sodium aluminium hydrides as potential new hydrogen storage materials. J Alloys Compd. 20003023658
  56. 56. NakamuraY.FossdalA.BrinksH. W.HaubackB. C.Characterization of Al-Ti phases in cycled TiF3enhanced Na2LiAlH6. J Alloys Compd. 2005
  57. 57. Brinks HW, Hauback BC, Srinivasan SS, Jensen CM.Synchrotron X-ray Studies of Al1-yTiy Formation and Re-hydriding Inhibition inTi-Enhanced NaAlH4. J Phys Chem B. 2005109157805
  58. 58. LéonA.YalovegaG.SoldatovA.FichtnerM.Investigation of the Nature of a Ti−Al Cluster Formed upon Cycling under Hydrogen in Na Alanate Doped with a Ti-Based Precursor. J Phys Chem C. 200811232125459
  59. 59. Majzoub EH, Gross KJ.Titanium-halide catalyst-precursors in sodium aluminum hydrides. J Alloys Compd. 2003363 EOF367 EOF
  60. 60. IniguezJ.YildirimT.First-principles study of Ti-doped sodium alanate surfaces. Appl Phys Lett. 2005Mar 7;86(10):103109 EOF
  61. 61. Balde CP, Stil HA, van der Eerden AMJ, de Jong KP, Bitter JH.Active Ti species in TiCl3-doped NaAlH4. Mechanism for catalyst deactivation. J Phys Chem C. 2007Feb;11162797802
  62. 62. GunaydinH.HoukK. N.OzolinsV.Vacancy-mediated dehydrogenation of sodium alanate. Proc Nat Acad Sci USA. 2008Mar 11;1051036737
  63. 63. StreukensG.BogdanovicB.FelderhoffM.SchuthF.Dependence of dissociation pressure upon doping level of Ti-doped sodium alanate-a possibility for’’thermodynamic tailoring’’ of the system. Phys Chem Chem Phys. 20068288992
  64. 64. LiuJ.GeQ. A.First-PrinciplesAnalysis.ofHydrogen.Interactionin.Ti-DopedNa.AlH.SurfacesStructure.EnergeticsJ, Ge Q. A First-Principles Analysis of Hydrogen Interaction in Ti-Doped NaAlH4 Surfaces: Structure and Energetics. J Phys Chem B. 2006110258638
  65. 65. Dathar GKP, Mainardi DS.Kinetics of Hydrogen Desorption in NaAlH4 and Ti-Containing NaAlH4. J Phys Chem C. 2010114802631
  66. 66. Anton DL.Hydrogen desorption kineitcs in transition metal modifed NaAlH4. J Alloys Compd. 2003
  67. 67. BogdanovićB.FelderhoffM.PommerinA.SchuthF.SpielkampN.Advanced Hydrogen-Storage Materials Based on Sc-, Ce-,and Pr-Doped NaAlH4. Adv Mater. 2006181198201
  68. 68. FangF.ZhangJ.ZhuJ.ChenG. R.SunD. L.HeB.et al.Nature and role of Ti species in the hydrogenation of a NaH/Al mixture. J Phys Chem C. 2007Mar 1;111834769
  69. 69. LiuJ.YuJ.GeQ.HydrideHydride-Assisted Hydrogenation of Ti-Doped NaH/Al: A Density Functional Theory Study. J Phys Chem C. 2011Feb 10;115525228
  70. 70. ClaudyP.BonnetotB.LettofféJ. M.TurckG.ThermochimActa. 19782721321
  71. 71. DymovaT. N.AleksandrovD. P.KonoplevV. N.SilinaT. A.ASSizarevaJ.CoordChem. 19942027985
  72. 72. Balema VP, Dennis KW, Pecharsky VP.Rapid solid-state transformation of tetrahedral AlH4- into octahedralAlH63- in lithium aluminohydride. Chem Commun. 2000200016656
  73. 73. Balema VP, Pecharsky VP, Dennis KW.Solid state phase transformations in LiAlH4 during high-energy ball-milling. J Alloys Compd. 200069 EOF74 EOF
  74. 74. BalemaV. P.WienchJ. M.DennisK. W.PruskiM. K. P. V.Titanium catalyzed solid-state transformations in LiAlH during high- energy ball-milling. J Alloys Compd. 200132910814
  75. 75. ChenJ.KuriyamaN.XuQ.TakeshitaH. T.SakaiT.Reversible hydrogen storage via titanium-catalyzed LiAlH4 and Li3AlH6. J Phys Chem B. 2001Nov 15;105451121420
  76. 76. Langmi HW, McGrady GS, Liu XF, Jensen CM.Modification of the H2 Desorption Properties of LiAlH(4) through Doping with Ti. J Phys Chem C. 2010Jun 17;11423106669
  77. 77. Liu XF, Langmi HW, Beattie SD, Azenwi FF, McGrady GS,Jensen CM. Ti-Doped LiAlH(4) for Hydrogen Storage: Synthesis, Catalyst Loading and Cycling Performance. J AmChemSoc. 2011Oct 5;13339155937
  78. 78. Lide DR. CRC Handbook of Chemistry and Physics.Boca Raton: CRC Press; 2004
  79. 79. ZüttelA.WengerP.RentschS.SudanP.MauronP.EmmeneggerC.LiB. H. a.newhydrogen.storagematerial.J Power Source. 200311817
  80. 80. ZüttelA.RentschS.FischerP.WengerP.SudanP.MauronP.et al.Hydrogen storage properties of LiBH4. J Alloys Compd. 2003515 EOF520 EOF
  81. 81. AuM.JurgensenA.ZeiglerK.Modified Lithium Borohydrides for Reversible Hydrogen Storage (2). J Phys Chem B. 200611051264827
  82. 82. AuM.JurgensenA.Modified Lithium Borohydrides for reversible hydrogen storage. J Phys Chem B. 200611070627
  83. 83. FangZ. Z.MaKangL. P.WangX. D.WangP. J.ChengP.H. M.In situ formation and rapid decompisition of Ti(BH4)3 by mechanical milling LiBH4 with TiF3. Appl Phys Lett. 2009
  84. 84. LiuJ.GeQ.Hydrogen Interaction in Ti-Doped LiBH4 for Hydrogen Storage: A Density Functional Analysis. J Chem Theo Comput. 2009Nov;511307987
  85. 85. ChlopekK.FrommenC.LeonA.ZabaraO.FichtnerM.Synthesis and properties of magnesium tetrahydroborate, Mg(BH4)2. JMater Chem. 200717333496503
  86. 86. LiH. W.KikuchiK.NakamoriY.MiwaK.TowataS.OrimoS.Effects of ball milling and additives on dehydriding behaviors of well-crystallized Mg(BH4)2. Scripta Materialia. 2007Oct;57867982
  87. 87. LiH. W.MiwaK.OhbaN.FujitaT.SatoT.YanY.et al.Formation of an intermediate compound with a B12H12 cluster: experimental and theoretical studies on magnesium borohydride Mg(BH4)2. Nanotechnology. 2009May 20;20202040138
  88. 88. SoloveichikG. L.AndrusM.GaoY.ZhaoJ. C.KniajanskiS.Magnesium borohydride as a hydrogen storage material: Synthesis of unsolvated Mg(BH4)2. Int J Hydrogen Energy. 2009Mar;345214452
  89. 89. YanY.LiH. W.NakamoriY.OhbaN.MiwaK.TowataS.et al.Differential Scanning Calorimetry Measurements of Magnesium Borohydride Mg(BH4)2. Mater Trans. 2008Nov;491127512
  90. 90. HanadaN.ChopekK.FrommenC.LohstrohW.FichtnerM.Thermal decomposition of Mg(BH4)2 under He flow and H2 pressure. J Mater Chem. 2008182226114
  91. 91. MDRiktorSorby. M. H.ChlopekK.FichtnerM.BuchterF.ZuettelA.et al.In situ synchrotron diffraction studies of phase transitions and thermal decomposition of Mg(BH4)2 and Ca(BH4)2. J Mater Chem. 20071747493942
  92. 92. MatsurtagaT.BuchterF.MiwaK.TowataS.OrimoS.ZuttelA.Magnesiumborohydride. A.newhydrogen.storagematerial.Renewable Energy. 2008Feb;3321936
  93. 93. VarinR. A.ChiuC.WronskiZ. S.Mechano-chemical activation synthesis (MCAS) of disordered Mg(BH4)2using NaBH4. J Alloys Compd. 2008Aug 25;462(1-2):201-8.
  94. 94. ChoudhuryP.BhethanabotlaV. R.StefanakosE.First principles study to identify the reversible reaction step of a multinary hydrogen storage "Li-Mg-B-N-H" system. IntJ Hydrogen Energy. 2010Sep;3517900211
  95. 95. BezemerG. L.BitterJ. H.KuipersH. P. C. E.OosterbeekH.HolewijnJ. E.XuX. D.et al.Cobalt particle size effects in the Fischer-Tropsch reaction studied with carbon nanofiber supported catalysts. J Am Chem Soc. 2006Mar 29;12812395664
  96. 96. Bell AT.The impact of nanoscience on heterogeneous catalysis. Science. 2003Mar 14;2995613168891
  97. 97. Xi JQ, Kim JK, Schubert EF.Silica nanorod-array films with very low refractive indices. Nano Lett. 2005Jul;5713857
  98. 98. TongL. M.LouJ. Y.GattassR. R.HeS. L.ChenX. W.LiuL.et al.Assembly of silica nanowires on silica aerogels for microphotonic devices. Nano Lett. 2005Feb;5225962
  99. 99. Baldé CP, Hereijgers BPC, BitterJH, de Jong KP. Sodium Alanate Nanoparticles- Linking Size to Hydrogen Storage Properties. J Am Chem Soc. 200813067615
  100. 100. LohstrohW.RothA.HahnH.FichtnerM.Thermodynamics Effects in Nanoscale NaAlH4. ChemPhysChem. 20101178992
  101. 101. FichtnerM.Properties of nanoscle metal hydrides. Nanotechnology. 2009
  102. 102. GaoJ.AdelhelmP.VerkuijlenM. H. W.RongeatC.HerrichM.BentumP. J. M.et al.Confinementof.NaAl. H.inNanoporous.CarbonImpact.onH.ReleaseReversibility.andmodynamicsJ.PhysChem.C. 2010114467583
  103. 103. KowalczykP.HolystR.TerronesM.TerronesH.Hydrogen storage in nanoporous carbon materials myth and facts. Phys Chem Chem Phys. 20079178692
  104. 104. BogdanovićB.FelderhoffM.PommerinA.SchüthF.SpielkampN.Advanced Hydrogen-Storage Materials Based on Sc-, Ce-,and Pr-Doped NaAlH4. Adv Mater. 2006181198201
  105. 105. FichtnerM.FuhrO.KircherO.RotheJ.Small Ti clusters for catalysis of hydrogen exchange in NaAlH4. NANOTECHNOLOGY. 20031477885
  106. 106. Vajo JJ, Olson GL.Hydrogen storage in destabilized chemical systems. Scripta Materialia. 2007May;561082934
  107. 107. Gross AF, Vajo JJ, Van Atta SL, Olson GL.Enhanced hydrogen storage kinetics of LiBH4 in nanoporous carbon scaffolds. J Phys Chem C. 2008Apr 10;1121456517
  108. 108. ZhangY.ZhangW. S.WangA. Q.SunL. X.FanM. Q.ChuH. L.et al.LiB. H.nanoparticlessupported.bydisordered.mesoporouscarbon.Hydrogenstorage.performancesdestabilizationmechanisms.Int J Hydrogen Energy. 2007Nov;3216397680
  109. 109. MSWellonsBerseth. P. A.ZidanR.Novel catalytic effects of fullerene for LiBH4 hydrogen uptake and release. Nanotechnology. 2009May 20;20(20).
  110. 110. LovvikO. M.SwangO.OpalkaS. M.Modeling alkali alanates for hydrogen storage by density-functional band-structure calculations. J Mater Res. 2005Dec;20123199213
  111. 111. Opalka SM, Lovvik OM, Brinks HW, Saxe PW, Hauback BC.Integrated experimental-theoretical investigation of the Na-Li-Al-H system. Inorg Chem. 2007Feb 19;46414019
  112. 112. HuotJ.BoilyS.GutherV.SchulzR.Synthesisof.NaAl. H.NaLi.AlH.bymechanical.alloyingJ.AlloysCompd.1999Feb 1;283(1-2):304 EOF306 EOF
  113. 113. BrinksH. W.HaubackB. C.JensenC. M.ZidanR.Synthesis and crystal structure of Na(2)LiAlD(6). J Alloys Compd. 2005Apr 19;392(1-2):27-30.
  114. 114. OrimoS.NakamoriY.KitaharaG.MiwaK.OhbaN.TowataS.et al.Dehydriding and rehydriding reactions of LiBH4. J Alloys Compd. 2005
  115. 115. MiwaK.OhbaN.TowataS.NakamoriY.OrimoS.First-principles study on copper-substituted lithium borohydride, (Li1-xCux)BH4. J Alloys Compd. 2005Dec 8;4041403
  116. 116. LiH. W.OrimoS.NakamoriY.MiwaK.OhbaN.TowataS.et al.Materials designing of metal borohydrides: Viewpoints from thermodynamical stabilities. J Alloys Compd. 2007Oct 31;4463158
  117. 117. HagemannH.LonghiniM.KaminskiJ. W.WesolowskiT. A.CernyR.PeninN.et al.LiSc. B.H4)novelA.saltof.LidiscreteSc. B.H4complexanions.JW, Wesolowski TA, Cerny R, Penin N, et al. LiSc(BH4)4: A novel salt of Li+ and discrete Sc(BH4)4 complex anions. J Phys Chem A. 2008Aug 21;1123375515
  118. 118. SorbyM. H.BrinksH. W.FossdalA.ThorshaugK.HaubackB. C.The crystal structure and stability of K2NaAlH6. J Alloys Compd. 2005284 EOF287 EOF
  119. 119. TangX.OpalkaS. M.LaubeB. L.WuF. J.StricklerJ. R.AntonD. L.Hydrogen storage properties of Na-Li-Mg-Al-H complex hydrides. J Alloys Compd. 2007Oct 31;44622831
  120. 120. GroveH.BrinksH. W.HeynR. H.WuF. J.OpalkaS. M.TangX.et al.The structure of LiMg(AlD4)3. J Alloys Compd. 2008May 8;455(1-2):249-54.
  121. 121. AuM.MJMezianiSun. Y. P.PinkertonF. E.Synthesis and Performance Evaluation of Bimetallic Lithium Borohydrides as Hydrogen Storage Media. Journal of Physical Chemistry C. 2011Oct 27;115422076573
  122. 122. FangZ. Z.KangX. D.LuoJ. H.WangP.LiH. W.OrimoS.Formation and Hydrogen Storage Properties of Dual-Cation (Li, Ca) Borohydride. J Phys Chem C. 2010Dec 30;114512273641
  123. 123. Jiang K, Xiao XZ, Deng SS, Zhang M, Li SQ, Ge HW, et al. A Novel Li-Ca-B-H Complex Borohydride: Its Synthesis and Hydrogen Storage Properties. J Phys Chem C C. 2011 Oct 13;115(40):19986-93.
  124. 124. BlanchardD.ShiQ.BoothroydC. B.VeggeT.Reversibility of Al/Ti Modified LiBH4. J Phys Chem C. 2009Aug 6;113311405966
  125. 125. CernyR.RavnsbaekD. B.SeveraG.FilinchukY.D’Anna. V.HagemannH.et al.Structure and Characterization of KSc(BH4)4. J Phys Chem C. 2010Nov 18;11445195409
  126. 126. CernyR.SeveraG.RavnsbaekD. B.FilinchukY.D’AnnaV.HagemannH.et al.NaSc. B.H(4))(4NovelA.Scandium-BasedBorohydride. J.PhysChem. C.2010Jan 21;1142135764
  127. 127. LodzianaZ.Multivalent metal tetrahydroborides of Al, Sc, Y, Ti, and Zr. Phys Rev B. 2010Apr 1;81(14).
  128. 128. YangJ.SudikA.WolvertonC.destabilizingLi. B. H.witha.metal.M=Mg.AlTi. V.Cror.scor.metalhydride. . M.H2=Mg. H.TiH.CaH2J, Sudik A, Wolverton C. destabilizing LiBH4 with a metal (M=Mg, Al, Ti, V, Cr, or sc) or metal hydride (MH2=MgH2, TiH2, CaH2). J Phys Chem C. 2007
  129. 129. NickelsE. A.JonesM. O.DavidW. I. F.JohnsonS. R.LowtonR. L.SommarivaM.et al.Tuning the decomposition temperature in complex hydrides: Synthesis of a mixed alkali metal borohydride. Angew Chem Int Ed. 2008471528179
  130. 130. SeballosL.ZhangJ. Z.RonnebroE.HerbergJ. L.MajzoubE. H.Metastability and crystal structure of the bialkali complex metal borohydride NaK(BH4)2. J Alloys Compd. 2009May 12;476(1-2):446-50.
  131. 131. KimC.HwangS. J.BowmanR. C.ReiterJ. W.ZanJ. A.KulleckJ. G.et al.LiSc. B.H4asHydrogena.StorageMaterial.Multinuclear-ResolutionHigh.Solid-StateN. M. R.First-PrinciplesDensity.FunctionalTheory.StudiesJ, Bowman RC, Reiter JW, Zan JA, Kulleck JG, et al. LiSc(BH4)4 as a Hydrogen Storage Material: Multinuclear High-Resolution Solid-State NMR and First-Principles Density Functional Theory Studies. J Phys Chem C. 2009Jun 4;11322995668
  132. 132. RavnsbaekD.FilinchukY.CereniusY.JakobsenH. J.BesenbacherF.SkibstedJ.etal. A.Seriesof.Mixed-MetalBorohydrides.Angew Chem Int Ed 20094836665963
  133. 133. Alapati SV, Johnson JK, Sholl DS.Using first principles calculations to identify new destabilized metalhydride reactions for reversible hydrogen storagew. Phys Chem Chem Phys. 20079143852
  134. 134. Alapati SV, Johnson JK, Sholl DS.Identification of destabilized metal hydrides for hydrogen storage using first principles calculations. J Phys Chem B. 2006May 4;11017876976
  135. 135. Alapati SV, Johnson JK, Sholl DS.Predicting reaction equilibria for destabilized metal hydride decomposition reactions for reversible hydrogen storage. J Phys Chem C. 2007Feb 1;1114158491
  136. 136. YuX. B.GrantD. M.WalkerG. S. A.newdehydrogenation.mechanismfor.reversiblemulticomponent.borohydride-Thesystems.roleof.Li-Mgalloys.Chem Commun. 200620063739068
  137. 137. WolvertonC.SiegelD. J.AkbarzadehA. R.OzolinsV.Discovery of novel hydrogen storage materials: an atomic scale computational approach. J PhysCondense Matt. 2008Feb 13;20(6).
  138. 138. SiegelD. J.WolvertonC.OzolinsV.Thermodynamic guidelines for the prediction of hydrogen storage reactions and their application to destabilized hydride mixtures. Phys Rev B. 2007Oct;76(13).
  139. 139. VajoJ. J.SkeithS. L.MertensF.Reversible storage of hydrogen in destabilized LiBH4. J Phys Chem B. 2005Mar 10;1099371922
  140. 140. Piinkerton FE, Meyer MS, Meisner GP, Balogh MP, Vajo JJ.Phase boundaries and reversibility of LiBH4/MgH2 hydrogen storage material. JPhys Chem C. 2007Sep 6;11135128815
  141. 141. BarkhordarianG.KlassenT.DornheimM.BormannR.Unexpected kinetic effect of MgB2 in reactive hydride composites containing complex borohydrides. J Alloys Compd. 2007Aug 16;440(1-2):L18L21.

Written By

Jianjun Liu and Wenqing Zhang

Submitted: March 28th, 2012 Published: September 5th, 2012

© 2012 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Continue reading from the same book

View All
Chapter 3 Enclosure of Sodium Tetrahydroborate (NaBH4) in So...

By Josef-Christian Buhl, Lars Schomborg and Claus Hen...

2819 downloads

Chapter 4 The Preparation and Hydrogen Storage Performances ...

By Yanghuan Zhang, Hongwei Shang, Chen Zhao and Dongl...

2467 downloads

Chapter 5 Hydrogen Storage Properties and Structure of Magne...

By Kazuhide Tanaka

3199 downloads