Hydrogen and Pd-clusters

Pundt, Astrid; Suleiman, Mohammed; Bähtz, C.; Reetz, Manfred T.; Kirchheim, R.; Jisrawi, N.

doi:10.1016/j.mseb.2003.10.029

Cited by 90 publications

(68 citation statements)

References 25 publications

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“…Pundt et al attributed the sloped plateau' of clusters to mechanical stress occurring between the Pd cluster and its surfactants during hydrogen sorption. [64] Clusters, studied by Züttel et al as well as those studied by Sachs et al and Pundt et al show a second slope change at concentrations lower than that of the bulk a¢-phase, whereas Abens second slope change tends to higher values. This complete shift can be understood: Aben heated the clusters (up to 650 C) to remove adsorbed surface hydrogen.…”

Section: Reviewsmentioning

confidence: 76%

See 1 more Smart Citation

Hydrogen in Nano‐sized Metals

Pundt¹

2004

Adv Eng Mater

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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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Section: Reviewsmentioning

confidence: 76%

“…This is in accordance with Wolf et al calculations. But, Pd-H clusters show a decreased width of the two-phase field which is the plateau-like region of the isotherm (as verified by x-ray diffraction, [63] and hysteresis occurrence [64] ). Thus, in contrast to Wolf et al calculations, a two phase field can be found in experiments.…”

Section: Reviewsmentioning

confidence: 78%

Hydrogen in Nano‐sized Metals

Pundt¹

2004

Adv Eng Mater

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148

101

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“…[87] However, others have shown that 5-nm Pd clusters do undergo structural change upon hydrogen absorption, probably from a cubic lattice to an icosahedral one. [88] Pd clusters loaded on carbon have been shown to absorb more hydrogen per Pd atom than does bulk Pd, [89] an effect attributed to spillover (a process whereby hydrogen spreads from a metal particle to its support). [90] The absorption was shown to be reversible but a significant fraction of the stored hydrogen required pressures of less than 5 Torr or high temperatures in order to be released.…”

Section: Giant Clusters Displaying Reversible H 2 Bindingmentioning

confidence: 99%

Reversible Binding of Dihydrogen in Multimetallic Complexes

Weller

McIndoe

2007

Eur J Inorg Chem

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The interaction of hydrogen with metal surfaces is one of the most important and fundamental processes in the chemical industry. Hydrogen is also strongly tipped to play a central role in new challenges that are emerging in terms of climate change and energy supply, and the reversible binding of H 2 to suitable materials will play a keystone role in the realisation of the hydrogen economy. The reversible interaction of hydrogen with multimetallic centres is also an important theme in biological processes; the role of hydrogenases in the metabolism of H 2 is an example. Thus the reversible interaction of H 2 with multimetallic metal complexes is an area that spans considerable breadth. This review is concerned

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“…Porous carbon has a high specific surface area [23], which suggests that the combination of these characteristics will significantly increase the possibilities of detection and makes these films ideal sensors of the hydrogen. It also showed that the nanocrystalline palladium can absorbs hydrogen [24,25], it can show a change in crystal structure [26] and in electrical conductivity [27] in hydrogen presence.…”

Section: Introductionmentioning

confidence: 95%