Abnormally large deuterium uptake on small transition metal clusters

Cox, D. M.; Fayet, Pierre; Brickman, R. O.; Hahn, M. Y.; Kaldor, A.

doi:10.1007/bf00765311

Cited by 53 publications

(32 citation statements)

References 34 publications

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“…Furthermore, edges and corner sites are available in clusters that additionally increase the cluster solubility compared to bulk. In extremely small clusters of less than 1 nm hydrogen to metal-atom ratios of 8 were reported [9]. From these results, it is expected that the border-phase solubility of clusters will be increased compared to bulk.…”

Section: Introductionmentioning

confidence: 87%

Hydrogen and Pd-clusters

Pundt

Suleiman

Bähtz

et al. 2004

Materials Science and Engineering: B

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Section: Introductionmentioning

confidence: 87%

Hydrogen and Pd-clusters

Pundt

Suleiman

Bähtz

et al. 2004

Materials Science and Engineering: B

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“…[86] Furthermore very high hydrogen/metal atomic ratios (up to 6) have been achieved for metal clusters that do not even form bulk hydrides, such as Ni, Co, Pt, Rh, and Sc. [87,88] For small clusters it is feasible to predict the structure and stability by using DFT or other computational approaches. For example, for MgH 2 ( Figure 11) it has been computed that the stability of the hydride decreases rapidly for particle sizes below 1.0 nm, and converges to bulk stability values for particle sizes above 2 nm.…”

Section: Particle Size Effectsmentioning

confidence: 99%

Nanosizing and Nanoconfinement: New Strategies Towards Meeting Hydrogen Storage Goals

2010

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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.

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“…[15,16] However, the local configuration of these small clusters might be completely different compared to the larger size system. [17,18] To conclude, surfaces offer sites which lead to a local increase of the hydrogen solubility.…”

Section: Surface Contributionsmentioning

confidence: 99%

Hydrogen in Nano‐sized Metals

Pundt¹

2004

Adv Eng Mater

148

101

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Nano-sized metal systems have received growing attention during the last decade which is not only motivated by the technological interest in low-dimensional systems providing the size reduction of electronic devices, but also by fundamental interest since physical properties tend to show interesting changes when the size of the system is reduced. So called finite-size effects become relevant as soon as the system-size is in the order of the correlation length of the system. Surface-as well as interface-effects influence strongly the system behaviour when their relative fraction compared to the volume increases. Furthermore, often substrate contributions influence the system properties. All these contributions become more relevant when the system size goes down to the nanometer-range. This range is, especially with regard to applications, a major field of interest: low-dimensional patterning of electronic devices still can increase the information density or might reduce the size of the product of interest. On the other hand, surface related processes, for example catalysts demand for nano-sized materials providing a large amount of active surface area. Physical properties of these systems, for example phase boundaries and lattice structures, tend to be quite different from those of the large size ªbulkº system. Therefore, the understanding of general rules or trends occurring at minimisation of metal-systems is an important problem that still needs to be solved.Nano-sized metal systems are mostly found in the shape of thin films, rods or clusters. Also stacking of nano-sized systems in so-called multi-layers causes interesting sample morphologies with a high density of interface volume (see Fig. 1).The physical properties of such nano-sized systems can be studied by choosing systems with a highly mobile alloying partner: the metal-hydrogen systems. The big advantage of such a system is that alloying is possible just by increasing the partial hydrogen-gas pressure (or chemical potential). According to Sieverts the concentration c H (given by the number of H-atoms per metal-atoms H/M) inside a metal is connected with the gas-pressure p H2 expressed by the solubility S 0 , c H =S 0 Öp H2 . [1] This equation holds for the low-concentration-range for all metals at the most up to the concentration where a hydride is formed. This concentration is called the solubility limit. The solubility S 0 varies significantly, for example for bulk Yttrium (Y) or Niobium (Nb) it is up to 10 11 or 10 3 , respectively, down to small values of 10 ±1 for bulk Palladium (Pd) or 10 ±20 for Tungsten (W). This implies huge differences in the hydrogen concentration for different metals at the same hydrogen gas pressure (chemical potential). However, the solubility for the nano-sized system can be different compared to bulk.Because of its small size and its ability to tunnel between neighbouring interstitial lattice sites, hydrogen is highly mobile. Diffusion constants such as 3´10 ±7 cm 2 /s for Pd (at 300 K) are usual, resulting in diffusio...

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Abnormally large deuterium uptake on small transition metal clusters

Cited by 53 publications

References 34 publications

Hydrogen and Pd-clusters

Hydrogen and Pd-clusters

Nanosizing and Nanoconfinement: New Strategies Towards Meeting Hydrogen Storage Goals

Hydrogen in Nano‐sized Metals

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