Special Issue "Bimetallic Catalysts—Application in Hydrogen Storage"

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A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (30 June 2012)

Special Issue Editor

Guest Editor
Dr. Zahir Dehouche (Website)

Department of Mechanical Engineering, Brunel University, Room H128, Uxbridge, UB8 3PH, UK
Interests: new materials and concepts in destabilized light reversible hydrides; colloidal nanocatalysts and high-surface-area materials for superior hydrogen storage

Special Issue Information

Dear Colleagues,

Hydrogen storage infrastructures became one of the major obstacles in the development of the global hydrogen energy economy structure, therefore materials for solid-state storage of hydrogen and containers for hydrogen storage are at the present time the most challenging and also the most demanded subject for innovative research. Currently known storage materials are unable to meet cost and performance targets to allow hydrogen-fuelled power sources to be a competitive alternative. Improving reversible hydrogen sorption rates of solid-state stores at moderate temperature are of great technological importance for the adoption of hydrogen for transportation and stationary applications. From large number of studies available, currently emerges a general perspective that optimum sorption hydrogen storage characteristics may be reached only in catalytically enhanced systems.
The aim of this special issue is to explore recent progress and novel trends in the ability of different binary and ternary metastable alloy catalysts to increase the kinetics of hydrogen uptake and release of nanostructured hydride composites, ranging from the basic research and high resolution and sensitivity characterization studies to the development of new hydrogen sorption nanocomposite formulations and modelling.

Dr. Zahir Dehouche
Guest Editor

Keywords

  • hydrogen storage materials;
  • alloy nanocatalysts;
  • nanostructured sorption composites;
  • thermodynamic, kinetic and cycling properties;
  • high resolution and sensitivity structural characterizations;
  • In-Situ neutron and X-ray scattering;
  • advanced microscopy;
  • modelling of hydrogen/sorption composite interactions

Published Papers (4 papers)

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Research

Open AccessArticle Enhancement of Hydrogen Storage Behavior of Complex Hydrides via Bimetallic Nanocatalysts Doping
Catalysts 2012, 2(4), 434-446; doi:10.3390/catal2040434
Received: 3 July 2012 / Revised: 28 August 2012 / Accepted: 28 September 2012 / Published: 17 October 2012
Cited by 1 | PDF Full-text (971 KB) | HTML Full-text | XML Full-text
Abstract
Pristine complex quaternary hydride (LiBH4/2LiNH2) and its destabilized counterpart (LiBH4/2LiNH2/nanoMgH2) have recently shown promising reversible hydrogen storage capacity under moderate operating conditions. The destabilization of complex hydride via nanocrystalline MgH2 apparently [...] Read more.
Pristine complex quaternary hydride (LiBH4/2LiNH2) and its destabilized counterpart (LiBH4/2LiNH2/nanoMgH2) have recently shown promising reversible hydrogen storage capacity under moderate operating conditions. The destabilization of complex hydride via nanocrystalline MgH2 apparently lowers the thermodynamic heat values and thus enhances the reversible hydrogen storage behavior at moderate temperatures. However, the kinetics of these materials is rather low and needs to be improved for on-board vehicular applications. Nanocatalyst additives such as nano Ni, nano Fe, nano Co, nano Mn and nano Cu at low concentrations on the complex hydride host structures have demonstrated a reduction in the decomposition temperature and overall increase in the hydrogen desorption reaction rates. Bi-metallic nanocatalysts such as the combination of nano Fe and nano Ni have shown further pronounced kinetics enhancement in comparison to their individual counterparts. Additionally, the vital advantage of using bi-metallic nanocatalysts is to enable the synergistic effects and characteristics of the two transitional nanometal species on the host hydride matrix for the optimized hydrogen storage behavior. Full article
(This article belongs to the Special Issue Bimetallic Catalysts—Application in Hydrogen Storage)
Open AccessArticle Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling
Catalysts 2012, 2(3), 400-411; doi:10.3390/catal2030400
Received: 30 July 2012 / Revised: 3 September 2012 / Accepted: 7 September 2012 / Published: 24 September 2012
Cited by 8 | PDF Full-text (4410 KB) | HTML Full-text | XML Full-text
Abstract
The effect of extended H2 sorption cycles on the structure and on the hydrogen storage performances of MgH2 powders with 5 wt% of Fe particle catalyst is reported. MgH2 powders with and without Fe have been ball milled under [...] Read more.
The effect of extended H2 sorption cycles on the structure and on the hydrogen storage performances of MgH2 powders with 5 wt% of Fe particle catalyst is reported. MgH2 powders with and without Fe have been ball milled under Argon, the doped MgH2 nanocomposite has been cycled under hydrogen pressure up to a maximum of 47 desorption and absorption cycles at 300 °C. After acceleration during the first 10 cycles, the kinetics behavior of doped MgH2 is constant after extended cycling, in terms of maximum storage capacity and rate of sorption. The major effect of cycling on particle morphology is the progressive extraction of Mg from the MgO shell surrounding the powder particles. The Mg extraction from the MgO shell leaves the catalyst particles inside the hydride particles. Many empty MgO shells are observed in the pure ball milled MgH2 upon cycling at higher temperature, suggesting that this enhancement of the extraction efficiency is related to the higher operating temperature which favors Mg diffusivity with respect to the H ion one. Full article
(This article belongs to the Special Issue Bimetallic Catalysts—Application in Hydrogen Storage)
Open AccessArticle Catalytic Effect of Nb2O5 in MgH2-Nb2O5 Ball-Milled Composites
Catalysts 2012, 2(3), 344-351; doi:10.3390/catal2030344
Received: 23 July 2012 / Revised: 15 August 2012 / Accepted: 29 August 2012 / Published: 10 September 2012
Cited by 3 | PDF Full-text (2322 KB) | HTML Full-text | XML Full-text
Abstract
We report a study on the desorption properties, crystallography and chemical state of MgH2 and 1 mol% Nb2O5 ball-milled composites. Desorption temperatures of the composites decreased with increase of ball-milling time. Size of MgH2 crystallites decreased during [...] Read more.
We report a study on the desorption properties, crystallography and chemical state of MgH2 and 1 mol% Nb2O5 ball-milled composites. Desorption temperatures of the composites decreased with increase of ball-milling time. Size of MgH2 crystallites decreased during ball-milling. Reduction of Nb2O5 after ball-milling was confirmed by tracing the chemical state of Nb and was further supported by TEM observation. The reduced phases may act as more effective catalysts improving the desorption properties. Full article
(This article belongs to the Special Issue Bimetallic Catalysts—Application in Hydrogen Storage)
Open AccessArticle Superior MgH2 Kinetics with MgO Addition: A Tribological Effect
Catalysts 2012, 2(3), 330-343; doi:10.3390/catal2030330
Received: 17 July 2012 / Revised: 26 July 2012 / Accepted: 31 July 2012 / Published: 13 August 2012
Cited by 7 | PDF Full-text (922 KB) | HTML Full-text | XML Full-text
Abstract
The kinetics of hydrogen absorption/desorption in magnesium can be improved without any catalysis assistance and MgO was found to be more effective than the best catalyst reported so far, i.e., Nb2O5. Herein, a quantitative analysis of the [...] Read more.
The kinetics of hydrogen absorption/desorption in magnesium can be improved without any catalysis assistance and MgO was found to be more effective than the best catalyst reported so far, i.e., Nb2O5. Herein, a quantitative analysis of the hydrogen kinetics in magnesium modified with MgO was performed in order to identify possible rate controlling mechanisms. While hydrogen absorption was found to be diffusion controlled as commonly reported, hydrogen desorption evolved from nucleation and growth to an interface controlled process depending on the desorption temperature. Comparison with the effect of Nb2O5 indicates that similar rate limiting steps occur regardless of the oxide additive. These findings are reconciled by considering the tribological effect of solid oxide additives, as a correlation between oxides electronegativity and improvement in hydrogen kinetics was found. Such a correlation clearly highlights the mechanical effect of solid oxides in facilitating the grinding and stabilisation of small magnesium particles for efficient and fast hydrogen kinetics. Full article
(This article belongs to the Special Issue Bimetallic Catalysts—Application in Hydrogen Storage)

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