Hydrogenation characteristics of air-exposed magnesium films

Léon, Aline; Knystautas, Émile J.; Huot, Jacques; Schulz, Robert

doi:10.1016/s0925-8388(02)00394-8

Cited by 61 publications

(49 citation statements)

References 18 publications

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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: 73%

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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confidence: 73%

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

et al. 2009

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“…Since the first review of hydrogen storage in thin films by Wenzl et al [5], hydrogen sorption in thin films have been studied in a variety of systems [6][7][8][9]. In a recent study, Léon et al [10] have successfully stored 7.5 wt% hydrogen in air exposed Mg thin films, though the temperature in this study was quite high (623 K). A drastic reduction in the stability of MgH 2 was reported by Higuchi et al [11] where Mg thin films were capped from both sides by Pd layers.…”

Section: Introductionmentioning

confidence: 83%

Hydrogen absorption in magnesium based crystalline thin films

Akyıldız

Özenbaş

Őztürk

2006

International Journal of Hydrogen Energy

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“…The low reactivity is mainly attributed to the oxidation of the magnesium surface and limited dissociation rate of hydrogen molecules on this oxidized metal surface. In addition, magnesium metal is difficult to activate and the metal, as well as the magnesium hydride, are very sensitive to contamination [1]. The strong bond between Mg and H provides MgH 2 with high thermodynamic stability, which has an enthalpy of formation of about À76 kJ/mol and a decomposition temperature of more than 300 8C [2].…”

Section: Introductionmentioning

confidence: 99%