Hydrogen kinetics in magnesium hydride: On different catalytic effects of niobium

Bazzanella, Nicola; Checchetto, R.; Miotello, A.; Sada, Cinzia; Mazzoldi, P.; Mengucci, P.

doi:10.1063/1.2218328

Cited by 44 publications

(43 citation statements)

References 11 publications

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“…3 we present the H 2 desorption kinetics of pure MgH 2 and of Nb-and Fe-doped [3][4][5][6][7]. We note that the activation energy pertinent to the diffusion-controlled transformation of the doped sample is very close to the value of the activation energy for H diffusion in the h-Mg phase [10].…”

Section: Resultsmentioning

confidence: 99%

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H2 storage efficiency and sorption kinetics in composite materials

Checchetto¹,

Bazzanella²,

Miotello³

et al. 2008

Journal of Physics and Chemistry of Solids

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We have prepared two different kind of composite materials for hydrogen storage and studied their H 2 storage capacity and desorption kinetics. The first composite material consists of magnesium containing transition metal nanoclusters distributed in the Mg matrix (Mg:TM): this composite material shows better H 2 desorption performances than pure Mg. This improvement is attributed to the role of the MgH 2 -TM nanocluster interface as preferential site for hexagonal Mg (h-Mg) nucleation and to the rapid formation of interconnected h-Mg domains where H diffusion during desorption occurs. The second composite material consists of LaNi 5 particles (size < 30 m) distributed in a polymeric matrix. The H 2 storage capacity is negligible at low metal content (50 wt. %) when the metal particles are completely embedded in the polymeric matrix. The H 2 storage capacity is comparable to that of the pure LaNi 5 powders at high metal content (80 wt. %) when a percolative distribution is assumed by the LaNi 5 particles: this evidence points out the role of metalmetal interfaces and of interconnected metallic networks for H transport.

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Section: Resultsmentioning

confidence: 99%

“…The first one consists on a Mg matrix containing transition metal (TM) nanoclusters dispersed in the Mg bulk: here, the second component plays its role in the catalysis of the H 2 sorption kinetics by reducing the typical H 2 sorption times by up to two orders of magnitude [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

H2 storage efficiency and sorption kinetics in composite materials

Checchetto¹,

Bazzanella²,

Miotello³

et al. 2008

Journal of Physics and Chemistry of Solids

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“…In sputtered Mg films [15,16], the effect of a substrate may drastically affect the hydride nucleation process as has been reported in optical studies [17][18][19]. To avoid substrate contributions, freestanding films are preferred if the difficulty involved in depositing and delaminating them while avoiding oxidation can be overcome [20][21][22]. In this study, we report a sandwich configuration for the deposition of such nanograined Mg-Ni films.…”

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confidence: 96%

“…However, the slow kinetics and high heat of formation necessitate the use of catalysts in order to achieve complete utilization so that it may meet the requirements for on-board hydrogen storage applications [10]. Palladium (Pd) and nickel (Ni) are two commonly used catalysts that could enhance for hydrogen dissociation.…”

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confidence: 99%

Hydrogen storage characteristics of nanograined free-standing magnesium–nickel films

et al. 2009

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Free-standing magnesium-nickel (Mg-Ni) films with extensive nanoscale grain structures were fabricated using a combination of pulsed laser deposition and film delaminating processes. Hydrogen sorption and desorption properties of the films, free from the influence of substrates, were investigated. Oxidation of the material was reduced through the use of a sandwiched free-standing film structure in which the top and bottom layers consist of nanometerthick Pd layers, which also acted as a catalyst to promote hydrogen uptake and release. Hydrogen storage characteristics were studied at three temperatures, 296, 232, and 180°C, where multiple sorption/desorption cycles were measured gravimetrically. An improvement in hydrogen storage capacity over the bulk Mg-Ni target material was found for the free-standing films. As shown from a Van't Hoff plot, the thermodynamic stability of the nanograined films is similar to that of Mg 2 Ni. These results suggest that free-standing films, of which better control of material compositions and microstructures can be realized than is possible for conven- The need for a safe, reliable, and efficient method of hydrogen storage for transportation applications is stronger now than ever before. This need has led to a continuous increase in both the breadth and depth of research in the field of hydrogen storage. Compressed gas, liquid hydrogen, and various chemical and metal hydride approaches have been proposed and studied over the past 20 years [1]. Despite extensive research effort, no definitive best method or best material has been identified. Weaknesses and difficulties for every method and material exist. Examples are the poor volumetric storage of hydrogen as a compressed gas, the boil off of liquid hydrogen, the poor irreversibility of chemical and metal hydrides [2].Metal hydrides consisting of a high fraction of lightweight elements have attracted much attention. The basic storage mechanisms of hydrogen by physisorption and chemisorption as well as the importance of catalysts have been elucidated [3][4][5]. More recently, the benefits of using nanometer-sized materials have also been explored [6][7][8]. Through nanostructuring, improvements in hydrogen uptake and release kinetics at little cost to hydrogen sorption capacities are possible. There are, however, very few material synthesis approaches that can generate a sufficient quantity of nanostructured light-weight metals (which are generally reactive upon exposure toward air and water) for reliable testing of their hydrogen storage properties. The majority of existing studies of metal hydrides are based on the characterization of ball-milled powders. For many materials of

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“…To further understand the dehydrogenation kinetics mechanism, the activation energy ( E a ) for dehydrogenation is determined by the JMA model and Arrhenius equation after fi tting the experimental data. [ 22 ] Figure 9 shows the Arrhenius plot for the above fi ve samples, which clearly shows that: i) all catalysts milled with MgH 2 increase the dehydrogenation kinetics (reducing E a ), suggesting dehydrogenation as the rate-limiting step (RLS) is controlled from catalyzed Mg nucleation to hydrogen diffusion; [ 23 ] …”

Section: Full Papermentioning

confidence: 98%

Catalytic De/Hydrogenation in Mg by Co‐Doped Ni and VO_x on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity

Jia

Cheng

Pan

et al. 2011

Advanced Energy Materials

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A multi‐component catalyst Ni‐VOx/AC (VOx is comprised of V2O5 and VO2, x = 2.18) was synthesized by a wet impregnation method. The synthesized Ni‐VOx/AC shows a superior catalytic effect on de/hydrogenation of Mg. The MgH2+Ni‐VOx/AC composites can absorb 6.2 wt.‐% hydrogen within only 1 min at 150 °C under a hydrogen pressure of 2 MPa and desorb 6.5 wt.‐% hydrogen within 10 min at 300 °C under an initial hydrogen pressure of 1 KPa, which overcomes a critical barrier for practical use of Mg as a hydrogen storage material. A significant decrease of activation energy (Ea) indicates that Ni‐VOx/AC catalyst is highly efficient for Mg de/hydrogenation, which may be ascribed to the synergistic effect of bimetals (metal oxides) and nanocarbon.

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Hydrogen kinetics in magnesium hydride: On different catalytic effects of niobium

Cited by 44 publications

References 11 publications

H2 storage efficiency and sorption kinetics in composite materials

H2 storage efficiency and sorption kinetics in composite materials

Hydrogen storage characteristics of nanograined free-standing magnesium–nickel films

Catalytic De/Hydrogenation in Mg by Co‐Doped Ni and VO_x on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity

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Hydrogen kinetics in magnesium hydride: On different catalytic effects of niobium

Cited by 44 publications

References 11 publications

H2 storage efficiency and sorption kinetics in composite materials

H2 storage efficiency and sorption kinetics in composite materials

Hydrogen storage characteristics of nanograined free-standing magnesium–nickel films

Catalytic De/Hydrogenation in Mg by Co‐Doped Ni and VOx on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity

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Catalytic De/Hydrogenation in Mg by Co‐Doped Ni and VO_x on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity