Showing papers on "Hydrogen storage published in 2010"

High capacity hydrogen storage materials: attributes for automotive applications and techniques for materials discovery

Abstract: Widespread adoption of hydrogen as a vehicular fuel depends critically upon the ability to store hydrogen on-board at high volumetric and gravimetric densities, as well as on the ability to extract/insert it at sufficiently rapid rates As current storage methods based on physical means—high-pressure gas or (cryogenic) liquefaction—are unlikely to satisfy targets for performance and cost, a global research effort focusing on the development of chemical means for storing hydrogen in condensed phases has recently emerged At present, no known material exhibits a combination of properties that would enable high-volume automotive applications Thus new materials with improved performance, or new approaches to the synthesis and/or processing of existing materials, are highly desirable In this critical review we provide a practical introduction to the field of hydrogen storage materials research, with an emphasis on (i) the properties necessary for a viable storage material, (ii) the computational and experimental techniques commonly employed in determining these attributes, and (iii) the classes of materials being pursued as candidate storage compounds Starting from the general requirements of a fuel cell vehicle, we summarize how these requirements translate into desired characteristics for the hydrogen storage material Key amongst these are: (a) high gravimetric and volumetric hydrogen density, (b) thermodynamics that allow for reversible hydrogen uptake/release under near-ambient conditions, and (c) fast reaction kinetics To further illustrate these attributes, the four major classes of candidate storage materials—conventional metal hydrides, chemical hydrides, complex hydrides, and sorbent systems—are introduced and their respective performance and prospects for improvement in each of these areas is discussed Finally, we review the most valuable experimental and computational techniques for determining these attributes, highlighting how an approach that couples computational modeling with experiments can significantly accelerate the discovery of novel storage materials (155 references)

Carbon Dioxide and Formic Acid - The couple for an environmental-friendly hydrogen storage?

Abstract: In search for future energy supplies the application of hydrogen as an energy carrier is seen as a prospective issue. However, the implementation of a hydrogen economy is suffering from several unsolved problems. Particularly challenging is the storage of appropriate amounts of hydrogen. In this context the utilization of carbon dioxide–formic acid for hydrogen storing is discussed.

Monodisperse nickel nanoparticles and their catalysis in hydrolytic dehydrogenation of ammonia borane.

Abstract: Monodisperse nickel nanoparticles are prepared from the reduction of Ni(acac)2 with borane tributylamine in the presence of oleylamine and oleic acid. Without any special treatment to remove the surfactants, the as-synthesized Ni nanoparticles supported on the Ketjen carbon support exhibit high catalytic activity in hydrogen generation from the hydrolysis of the ammonia−borane (H3NBH3) complex with a total turnover frequency value of 8.8 mol of H2·(mol of Ni)−1·min−1. Such catalysis based on Ni nanoparticles represents a promising step toward the practical development of the H3NBH3 complex as a feasible hydrogen storage medium for fuel cell applications.

Catalytic Generation of Hydrogen from Formic acid and its Derivatives: Useful Hydrogen Storage Materials

Abstract: In this account the concept of using formic acid as a hydrogen storage material is presented. Catalytic reduction of carbon dioxide and heterogeneously catalyzed decomposition of formic acid to hydrogen and carbon dioxide are briefly discussed. In the main part the historic development and recent examples of homogeneously catalyzed hydrogen generation from formic acid are covered in detail.

Liquid‐Phase Chemical Hydrogen Storage: Catalytic Hydrogen Generation under Ambient Conditions

Abstract: There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

Using first principles to predict bimetallic catalysts for the ammonia decomposition reaction

Abstract: The facile decomposition of ammonia to produce hydrogen is critical to its use as a hydrogen storage medium in a hydrogen economy, and although ruthenium shows good activity for catalysing this process, its expense and scarcity are prohibitive to large-scale commercialization. The need to develop alternative catalysts has been addressed here, using microkinetic modelling combined with density functional studies to identify suitable monolayer bimetallic (surface or subsurface) catalysts based on nitrogen binding energies. The Ni-Pt-Pt(111) surface, with one monolayer of Ni atoms residing on a Pt(111) substrate, was predicted to be a catalytically active surface. This was verified using temperature-programmed desorption and high-resolution electron energy loss spectroscopy experiments. The results reported here provide a framework for complex catalyst discovery. They also demonstrate the critical importance of combining theoretical and experimental approaches for identifying desirable monolayer bimetallic systems when the surface properties are not a linear function of the parent metals.

Hydrogen Storage in Metal–Organic Frameworks

Abstract: Metal-organic frameworks (MOFs) are highly attractive materials because of their ultra-high surface areas, simple preparation approaches, designable structures, and potential applications. In the past several years, MOFs have attracted worldwide attention in the area of hydrogen energy, particularly for hydrogen storage. In this review, the recent progress of hydrogen storage in MOFs is presented. The relationships between hydrogen capacities and structures of MOFs are evaluated, with emphasis on the roles of surface area and pore size. The interaction mechanism between H(2) and MOFs is discussed. The challenges to obtain a high hydrogen capacity at ambient temperature are explored.

Calcium-Decorated Graphene-Based Nanostructures for Hydrogen Storage

Abstract: We report a first-principles study of hydrogen storage media consisting of calcium atoms and graphene-based nanostructures. We find that Ca atoms prefer to be individually adsorbed on the zigzag edge of graphene with a Ca−Ca distance of 10 A without clustering of the Ca atoms, and up to six H2 molecules can bind to a Ca atom with a binding energy of ∼0.2 eV/H2. A Ca-decorated zigzag graphene nanoribbon (ZGNR) can reach the gravimetric capacity of ∼5 wt % hydrogen. We also consider various edge geometries of the graphene for Ca dispersion.

Multifunctional Porous Graphene for Nanoelectronics and Hydrogen Storage: New Properties Revealed by First Principle Calculations

Abstract: The lack of an obvious “band gap” is a formidable hurdle for making a nanotransistor from graphene. Here, we use density functional calculations to demonstrate for the first time that porosity such as evidenced in recently synthesized porous graphene (http://www.sciencedaily.com/releases/2009/11/091120084337.htm) opens a band gap. The size of the band gap (3.2 eV) is comparable to most popular photocatalytic titania and graphitic C3N4 materials. In addition, the adsorption of hydrogen on Li-decorated porous graphene is much stronger than that in regular Li-doped graphene due to the natural separation of Li cations, leading to a potential hydrogen storage gravimetric capacity of 12 wt %. In light of the most recent experimental progress on controlled synthesis, these results uncover new potential for the practical application of porous graphene in nanoelectronics and clean energy.

Iron-Catalyzed Hydrogen Production from Formic Acid

Abstract: Hydrogen represents a clean energy source, which can be efficiently used in fuel cells generating electricity with water as the only byproduct. However, hydrogen generation from renewables under mild conditions and efficient hydrogen storage in a safe and reversible manner constitute important challenges. In this respect formic acid (HCO2H) represents a convenient hydrogen storage material, because it is one of the major products from biomass and can undergo selective decomposition to hydrogen and carbon dioxide in the presence of suitable catalysts. Here, the first light-driven iron-based catalytic system for hydrogen generation from formic acid is reported. By application of a catalyst formed in situ from inexpensive Fe3(CO)12, 2,2′:6′2′′-terpyridine or 1,10-phenanthroline, and triphenylphosphine, hydrogen generation is possible under visible light irradiation and ambient temperature. Depending on the kind of N-ligands significant catalyst turnover numbers (>100) and turnover frequencies (up to 200 h−1)...

Tunable Band Gap in Hydrogenated Quasi-Free-Standing Graphene

Abstract: We show by angle-resolved photoemission spectroscopy that a tunable gap in quasi-free-standing monolayer graphene on Au can be induced by hydrogenation. The size of the gap can be controlled via hydrogen loading and reaches ∼1.0 eV for a hydrogen coverage of 8%. The local rehybridization from sp2 to sp3 in the chemical bonding is observed by X-ray photoelectron spectroscopy and X-ray absorption and allows for a determination of the amount of chemisorbed hydrogen. The hydrogen induced gap formation is completely reversible by annealing without damaging the graphene. Calculations of the hydrogen loading dependent core level binding energies and the spectral function of graphene are in excellent agreement with photoemission experiments. Hydrogenation of graphene gives access to tunable electronic and optical properties and thereby provides a model system to study hydrogen storage in carbon materials.

Nanosizing and Nanoconfinement: New Strategies Towards Meeting Hydrogen Storage Goals

Abstract: Hydrogen is expected to play an important role as an energy carrier in a future, more sustainable society. However, its compact, efficient, and safe storage is an unresolved issue. One of the main options is solid-state storage in hydrides. Unfortunately, no binary metal hydride satisfies all requirements regarding storage density and hydrogen release and uptake. Increasingly complex hydride systems are investigated, but high thermodynamic stabilities as well as slow kinetics and poor reversibility are important barriers for practical application. Nanostructuring by ball-milling is an established method to reduce crystallite sizes and increase reaction rates. Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. In this Review we discuss the large impact of nanosizing and -confinement on the hydrogen sorption properties of metal hydrides. We illustrate possible preparation strategies, provide insight into the reasons for changes in kinetics, reversibility and thermodynamics, and highlight important progress in this field. All in all we provide the reader with a clear view of how nanosizing and -confinement can beneficially affect the hydrogen sorption properties of the most prominent materials that are currently considered for solid-state hydrogen storage.

Ammonia Borane as a Hydrogen Carrier: Dehydrogenation and Regeneration

Abstract: Interest in sustainable non-hydrocarbon-based fuels for transportation has grown as the realization that the supply of fossil fuels is limited and the deleterious environmental effects of burning them has come into public focus. The use of hydrogen (H2) has been proposed as an alternative, but its use in pure form is undesirable due to the high pressures or low temperatures required to store useful quantities. Approaches to ameliorate this issue, which stem from the low volumetric energy density of H2, include the pursuit of sorbents capable of containing H2 in greater density than liquid H2 at reasonable temperatures and pressures, metal hydrides such as NaBH4, and chemical hydrides such as ammonia borane (AB, NH3BH3). AB contains 19.6 wt.-% H2, which is well suited to practical applications, but issues with extracting the optimal quantities of H2 at reasonable temperatures and at useful rates as well as recycling of the spent fuel back into AB with good efficiency and reasonable cost remain to be solved. These problems are inextricably intertwined, as the needs of the regeneration process dictate which catalysts are used (i.e. what kind of spent fuel is generated). This Microreview focuses on recent developments in transition metal complexes for the catalytic dehydrogenation of AB. Neither solvolysis of AB nor thermolysis of AB in the absence of a catalyst are covered in this review.

Hydrogen storage and carbon dioxide capture in an iron-based sodalite-type metal–organic framework (Fe-BTT) discovered via high-throughput methods

Abstract: Using high-throughput instrumentation to screen conditions, the reaction between FeCl2 and H3BTT·2HCl (BTT3− = 1,3,5-benzenetristetrazolate) in a mixture of DMF and DMSO was found to afford Fe3[(Fe4Cl)3(BTT)8]2·22DMF·32DMSO·11H2O. This compound adopts a porous three-dimensional framework structure consisting of square [Fe4Cl]7+ units linked via triangular BTT3− bridging ligands to give an anionic 3,8-net. Mossbauer spectroscopy carried out on a DMF-solvated version of the material indicated the framework to contain high-spin Fe2+ with a distribution of local environments and confirmed the presence of extra-framework iron cations. Upon soaking the compound in methanol and heating at 135 °C for 24 h under dynamic vacuum, most of the solvent is removed to yield Fe3[(Fe4Cl)3(BTT)8(MeOH)4]2 (Fe-BTT), a microporous solid with a BET surface area of 2010 m2 g−1 and open Fe2+ coordination sites. Hydrogen adsorption data collected at 77 K show a steep rise in the isotherm, associated with an initial isosteric heat of adsorption of 11.9 kJ mol−1, leading to a total storage capacity of 1.1 wt% and 8.4 g L−1 at 100 bar and 298 K. Powder neutron diffraction experiments performed at 4 K under various D2 loadings enabled identification of ten different adsorption sites, with the strongest binding site residing just 2.17(5) A from the framework Fe2+ cation. Inelastic neutron scattering spectra are consistent with the strong rotational hindering of the H2 molecules at low loadings, and further reveal the catalytic conversion of ortho-H2 to para-H2 by the paramagnetic iron centers. The exposed Fe2+ cation sites within Fe-BTT also lead to the selective adsorption of CO2 over N2, with isotherms collected at 298 K indicating uptake ratios of 30.7 and 10.8 by weight at 0.1 and 1.0 bar, respectively.

Solid‐state Materials and Methods for Hydrogen Storage: A Critical Review

Abstract: Hydrogen is important as a new source of energy for automotive applications. It is clear that the key challenge in developing this technology is hydrogen storage. Current methods for hydrogen storage have yet to meet all the demands for on-board applications. High-pressure gas storage or liquefaction cannot fulfill the storage criteria required for on-board storage. Solid-state materials have shown potential advantages for hydrogen storage in comparison to other storage methods. In this article, the most popular solid-state storage materials and methods including carbon based materials, metal hydrides, metal organic frameworks, hollow glass microspheres, capillary arrays, clathrate hydrates, metal nitrides and imides, doped polymer and zeolites, are critically reviewed. The survey shows that most of the materials available with high storage capacity have disadvantages associated with slow kinetics and those materials with fast kinetics have issues with low storage capacity. Most of the chemisorption-based materials are very expensive and in some cases, the hydrogen absorption/desorption phenomena is irreversible. Furthermore, a very high temperature is required to release the adsorbed hydrogen. On the other hand, the main drawback in the case of physisorption-based materials and methods is their lower capacity for hydrogen storage, especially under mild operating conditions. To accomplish the requisite goals, extensive research studies are still required to optimize the critical parameters of such systems, including the safety (to be improved), security (to be available for all), cost (to be lowered), storage capacity (to be increased), and the sorption-desorption kinetics (to be improved).

Lithium-doped conjugated microporous polymers for reversible hydrogen storage.

Abstract: Hydrogen storage is of great interest as environmentally clean and efficient fuels are required for future energy applications. Several pioneering strategies have been developed and significant performances have been achieved for hydrogen storage, including chemisorption of dihydrogen in the form of light metal hydrides, metal nitrides and imides, physisorption of dihydrogen onto carbon, clathrate hydrates, and porous network materials such as carbon nanotubes (CNTs), zeolites, and metal–organic framework (MOF) materials. However, hydrogen storage in these systems requires either high pressure or very low temperature, or both, thus severely limiting the applicability for mobile applications, which require working conditions of 1– 20 bar and ambient temperature. The synthesis of functional materials with high hydrogen uptake and delivery under safe and ambient conditions remains a key challenge for establishing hydrogen economy. It has been reported that atomically dispersed alkalimetal ions (e.g., Li andNa) are capable of clustering several H2 molecules bound through electrostatic charge–quadrupole and charge-induced dipole interactions. Thus ab initio simulations showed that Li-doped pillared graphene can bind reversibly up to 6.5 mass% of H2 at 20 bar at room temperature. In addition, ab initio simulations showed that doping of MOFs with atomically dispersed alkali-metal cations can reversibly achieve up to 5.5 mass% of H2 at 100 bar at room temperature. These results suggest that the high electron affinity of the sp carbon framework can essentially separate the charge from the Li center, thus providing strong stabilization of the molecular H2 and dramatically improving the hydrogen uptake value compared to that of undoped systems. Recently, experimental investigations also showed that H2 uptake of the MOFs can be remarkably improved by introduction of Li ions into MOF systems. For instance, an Li-doped MOF, which was prepared by reaction of lithium diisopropylamide (LDA) with theMOF MIL-53(Al), was reported to exhibit nearly double the hydrogen uptake compared with an undoped MOF. The doping of Li into the MOF has also been reported to remarkably enhance the isosteric heats of H2 adsorption compared to those of the undoped MOF. To date, no material that consists of an active Li dopant and has ultrahigh hydrogen storage capacity has been reported. The difficulty in demonstrating this concept relates to whether agglomeration of the Li atoms occurs during synthesis. Recently, conjugated microporous polymers (CMPs) have received considerable research interest for hydrogen storage because of their finely tunable microporosity, large surface areas, and high stability. Herein, we report the first experimental evidence that Li ion dopants dramatically enhance hydrogen storage in a CMP matrix. The hydrogen storage amount can reach up to 6.1 wt% at 1 bar and 77 K, which is among the best reported to date for physisorption hydrogen storage materials including MOFs and CNTs. The CMP we selected was produced from 1,3,5-triethynylbenzene, which has active sites (C C bonds) for binding of metallic ions, large BET surface areas with microporous character, and good chemical (totally insoluble in all organic solvents), and thermal stability (thermogravimetric analysis (TGA) shows that the thermal decomposition temperature of the CMP is greater than 300 8C). These physicochemical properties suggest that the selected CMP is appropriate as a host for Li doping. Also, this material contains only three kinds of light elements (C, H, and Li), which is a great advantage for gravimetric adsorption. We synthesized the CMP by Pd/Cu-catalyzed homocoupling polymerization. To dope the CMP with Li, we immersed the CMP in a solution of the naphthalene anion radical salt (LiC10H8C ) in THF. The mixture was stirred for several hours under an inert atmosphere to allow thorough penetration of Li ions into the CMP network. The mixture was filtered and the solid product was washed with dry THF several times followed by removal of the solvent at room temperature and subsequent removal of the naphthalene under vacuum at 120 8C. The field emission scanning electron microscopy (FE-SEM) images (Figure 1a,b) show that the CMP and Li-CMP consist of agglomerated microgel particles and have porous features. TGA shows that the CMP have good thermal stability (Figure 1c, thermal decomposition temperature> 300 8C). In the case of the CMP treated with LiC10H8C (0.5 wt% Li), an obvious weight loss (ca. 10%) was observed in the temperature range 100–150 8C. This feature suggests the removal of the residual naphthalene absorbed in the CMP matrix, and is consistent with a previous report. Figure 1d shows the high-resolution [*] K.-L. Han, Prof. W.-Q. Deng State Key Lab of Molecular Reaction Dynamics Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 (China) E-mail: dengwq@dicp.ac.cn Homepage: http://www.nmce.dicp.ac.cn/

Handbook of hydrogen storage : new materials for future energy storage

Abstract: Preface STORAGE OF HYDROGEN IN THE PURE FORM Introduction Thermodynamic State and Properties Gaseous Storage Liquid Storage Hybrid Storage Comparison of Energy Densities Conclusion PHYSISORPTION IN POROUS MATERIALS Introduction Carbon Materials Organic Polymers Zeolites Coordination Polymers Conclusions CLATHRATE HYDRATES Introduction Clathrate Hydrate Structures Hydrogen Clathrate Hydrate Kinetic Aspects of Hydrogen Clathrate Hydrate Modeling of Hydrogen Clathrate Hydrates Future of Hydrogen Storage METAL HYDRIDES Introduction Elemental Hydrides Thermodynamics of Metal Hydrides Intermetallic Compounds Practical Considerations Metal Hydrides Systems Nanocrystalline Mg and Mg-Based Alloys Conclusion COMPLEX HYDRIDES Introduction Complex Borohydrides Complex Aluminum Hydrides Complex Transition Metal Hydrides Summary AMIDES, IMIDES AND MIXTURES Introduction Hydrogen Storage Properties of Amide and Imide Systems Structural Properties of Amide and Imide Prospects of Amide and Imide Systems Proposed Mechanism of the Hydrogen Storage Reaction in the Metal?N?H Systems Summary TAILORING REACTION ENTHALPIES OF HYDRIDES Introduction Thermodynamic Limitations of Lightweight Hydrides Strategies to Alter the Reaction Enthalpies of Hydrides Summary and Conclusion AMMONIA BORANE AND RELATED COMPOUNDS AS HYDROGEN SOURCE MATERIALS Introduction Materials Description and Characterization Production Thermally Induced Decomposition of Pure Ammonia Borane ALUMINUM HYDRIDE (ALANE) Introduction Hydrogen Solubility and Diffusivity in Aluminum Formation and Thermodynamics of Different Phases of Alane Stability and Formation of Adduct Organo-Aluminum Hydride Compounds Phases and Structures of Aluminum Hydride Novel Attempts and Methods for Forming Alane Reversibly Conclusion NANOPARTICLES AND 3D SUPPORTED NANOMATERIALS Introduction Particle Size Effects Non-Supported Clusters, Particles and Nanostructures Support Effects Preparation of Three-Dimensional Supported Nanomaterials Experimental Results on 3D-Supported Nanomaterials Conclusions and Outlook

Sodium Borohydride Hydrolysis as Hydrogen Generator: Issues, State of the Art and Applicability Upstream from a Fuel Cell

Abstract: Today there is a consensus regarding the potential of NaBH4 as a good candidate for hydrogen storage and release via hydrolysis reaction, especially for mobile, portable and niche applications. However as gone through in the present paper two mains issues, which are the most investigated throughout the open literature, still avoid NaBH4 to be competitive. The first one is water handling. The second one is the catalytic material used to accelerate the hydrolysis reaction. Both issues are object of great attentions as that can be noticed throughout the open literature. This review presents and discusses the various strategies which were considered until now by many studies to manage water and to improve catalysts performances (reactivity and durability). Published studies show real improvements and much more efforts might lead to significant overhangs. Nevertheless the results show that we are still far from envisaging short-term commercialization.

Ammonia Borane Confined by a Metal−Organic Framework for Chemical Hydrogen Storage: Enhancing Kinetics and Eliminating Ammonia

Abstract: A system involving ammonia borane (AB) confined in a metal−organic framework (JUC-32-Y) was synthesized. The hypothesis of nanoconfinement and metallic catalysis was tested and found to be effective for enhancing the hydrogen release kinetics and preventing the formation of ammonia. The AB in JUC-32-Y started to release hydrogen at a temperature as low as 50 °C. The peak temperature of decomposition decreased 30 °C (shifted to 84 °C). AB inside JUC-32-Y can release 8.2 wt % hydrogen in 3 min at 95 °C and 8.0 and 10.2 wt % hydrogen within 10 min at 85 °C.

Electric field enhanced hydrogen storage on polarizable materials substrates

Abstract: Using density functional theory, we show that an applied electric field can substantially improve the hydrogen storage properties of polarizable substrates. This new concept is demonstrated by adsorbing a layer of hydrogen molecules on a number of nanomaterials. When one layer of H2 molecules is adsorbed on a BN sheet, the binding energy per H2 molecule increases from 0.03 eV/H2 in the field-free case to 0.14 eV/H2 in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt% is consistent with the 6 wt% system target set by Department of Energy for 2010. The strength of the electric field can be reduced if the substrate is more polarizable. For example, a hydrogen adsorption energy of 0.14 eV/H2 can be achieved by applying an electric field of 0.03 a.u. on an AlN substrate, 0.006 a.u. on a silsesquioxane molecule, and 0.007 a.u. on a silsesquioxane sheet. Thus, application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H2 molecules can be easily released, thus making storage reversible with fast kinetics. In addition, we show that materials with rich low-coordinated nonmetal anions are highly polarizable and can serve as a guide in the design of new hydrogen storage materials.

Synthesis of a stable adduct of dialane(4) (Al2H4) via hydrogenation of a magnesium(I) dimer.

Abstract: The desorption of dihydrogen from magnesium(II) hydride, MgH2 (containing 7.6 wt% H), is reversible. MgH2 therefore holds promise as a hydrogen storage material in devices powered by fuel cells. We believed that dimeric magnesium(I) dimers (LMgMgL, L=β-diketiminate) could find use as soluble models to aid the study of the mechanisms and/or kinetics of the hydrogenation of magnesium and its alloys. Here, we show that LMgMgL can be readily hydrogenated to yield LMg(µ-H)2MgL by treatment with aluminium(III) hydride complexes. In one case, hydrogenation was reversed by treating LMg(µ-H)2MgL with potassium metal. The hydrogenation by-products are the first thermally stable, neutral aluminium(II) hydride complexes to be produced, one of which, [{(IPr)(H)2Al}2] (IPr=:C[{(C6H3-i-Pr(2)-2,6)NCH}2]), is an N-heterocyclic carbene adduct of the elusive parent dialane4 (Al2H4). A computational analysis of this compound is presented.

A reversible nanoconfined chemical reaction.

Abstract: Hydrogen is recognized as a potential, extremely interesting energy carrier system, which can facilitate efficient utilization of unevenly distributed renewable energy. A major challenge in a future “hydrogen economy” is the development of a safe, compact, robust, and efficient means of hydrogen storage, in particular, for mobile applications. Here we report on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. LiBH4 and MgH2 nanoparticles are embedded in a nanoporous carbon aerogel scaffold with pore size Dmax ∼ 21 nm and react during release of hydrogen and form MgB2. The hydrogen desorption kinetics is significantly improved compared to bulk conditions, and the nanoconfined system has a high degree of reversibility and stability and possibly also improved thermodynamic properties. This new scheme of nanoconfined chemistry may have a wide range of interesting applications in the future, for example, within the merging area of chemical storage of renewable energy.

Hydrogen storage in water-stable metal–organic frameworks incorporating 1,3- and 1,4-benzenedipyrazolate

Abstract: Pyrazolate-bridged metal–organic frameworks incorporating tetrahedral Zn2+ ions are shown to exhibit a high chemical stability in boiling water, organic solvents, and acidic media, and are assessed for their hydrogen storage properties.