Metal oxides as catalysts for improved hydrogen sorption in nanocrystalline Mg-based materials

Oelerich, W.; Klassen, Thomas; Bormann, R.

doi:10.1016/s0925-8388(00)01284-6

Cited by 747 publications

(420 citation statements)

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“…[1][2][3][4][5][6][7][8][9][10] Recently, many research groups have extensively investigated the various properties of metal oxide nanostructures with different dimensions (D) and they observed that only few of these metal oxide possess either d 0 (TiO 2 , WO 3 electronic configuration of cations exhibit feasible gas sensing properties. 11 Although there exist a few metal oxides with a d n (0 < n < 10) configuration of cations (NiO, VO 2 , Cr 2 O 3 , RuO 2 etc.)…”

Section: Introductionmentioning

confidence: 99%

Probing the highly efficient room temperature ammonia gas sensing properties of a luminescent ZnO nanowire array prepared via an AAO-assisted template route

et al. 2014

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Here, we report the facile synthesis of a highly ordered luminescent ZnO nanowire array using a low temperature anodic aluminium oxide (AAO) template route which can be economically produced in large scale quantity. The as-synthesized nanowires have diameters ranging from 60 to 70 nm and length ∼11 µm. The photoluminescence spectrum reveals that the AAO/ZnO assembly has a strong green emission peak at 490 nm upon excitation at a wavelength of 406 nm. Furthermore, the ZnO nanowire array-based gas sensor has been fabricated by a simple micromechanical technique and its NH 3 gas sensing properties have been explored thoroughly. The fabricated gas sensor exhibits excellent sensitivity and fast response to NH 3 gas at room temperature. Moreover, for 50 ppm NH 3 concentration, the observed value of sensitivity is around 68%, while the response and recovery times are 28 and 29 seconds, respectively. The present synthesis technique to produce a highly ordered ZnO nanowire array and a fabricated gas sensor has great potential to push the low cost gas sensing nanotechnology.

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Section: Introductionmentioning

confidence: 99%

Probing the highly efficient room temperature ammonia gas sensing properties of a luminescent ZnO nanowire array prepared via an AAO-assisted template route

et al. 2014

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“…Figure 1 10 alloys in the as-spun state, after three cycles of hydrogen absorption-desorption and of the heat treated sample in a continue heating up to 360ºC.…”

Section: Resultsmentioning

confidence: 99%

“…However, some peaks in the diffractograms could not be identified. The indexed phases after the heat treatment correspond to Mg 2 Cu and Mg 4 CuMM phases and the un-identified peaks present in the diffractogram after 10 , were produced from pure elements by diffusion of filed Cu particles in a Mg-MM or Mg-MM-Al molten alloy in a graphite crucible under Argon atmosphere in an electric furnace at 950 o C. The other master alloys were prepared by melting of pure elements in an induction furnace in a graphite crucible under argon atmosphere.…”

Section: Resultsmentioning

confidence: 99%

“…10 and Mg 65 Cu 10 Al 15 MM 10 alloys respectively. These alloys were tested to three consecutive cycles of hydrogen absorptiondesorption.…”

Section: Resultsmentioning

confidence: 99%

“…However, the hydrogen absorption-desorption kinetics are low and need high temperature (from 300ºC to 400ºC) due to the large formation enthalpy of the Mg hydride and diffusion properties. Possible ways to improve the hydrogen absorption-desorption kinetics are alloying Mg to modify the crystal structure of the hydrides by addition of transition metals, metal oxides or rare earths [7][8][9][10][11][12][13][14][15] , reducing the grain size by alloying elements, mechanical deformation or rapid solidification. In recent years the absorption-desorption of hydrogen in Mg alloys produced by unconventional methods have been investigated [16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

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Effect of Alloying Elements in Melt Spun Mg-alloys for Hydrogen Storage

et al. 2016

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In this paper we report the effect of alloying elements on hydrogen storage properties of meltspun Mg-based alloys. The base alloys Mg 90 Si 10 , Mg 90 Cu 10 , Mg 65 Cu 35 (at%) were studied. We also investigated the effect of rare earths (using MM: mischmetal) alloys showed an amorphous and partially amorphous structure respectively. At 350˚C all the alloys had a crystalline structure during the hydrogen absorption-desorption tests. It was observed that Si and Cu in the binaries alloys hindered completely the activation of the hydrogen absorption. The partial substitution of Cu by MM or Al allowed activation. The combined substitution of Cu by MM and Al showed the best results with the fastest absorption and desorption kinetics, which suggests that this combination can be used for new Mg-alloys to improve hydrogen storage properties.

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Hydrogen Sorption of Nanocrystalline Mg at Reduced Temperatures by Metal-Oxide Catalysts

Oelerich¹,

Klassen

Bormann

2001

Adv. Eng. Mater.

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Hydrogen is the ideal means of storage, transport, and conversion of energy in a comprehensive clean-energy concept. One major problem is the storage of hydrogen for use as a zero-emission vehicle fuel. Metal hydrides offer a safer alternative than storage in compressed or liquid form, and metal hydrides have the highest storage capacity by volume. Mg hydride also has a high storage capacity by weight and is therefore favored for mobile applications. However, light metal hydrides have not been considered competitive because of their rather sluggish sorption kinetics. Filling a tank could take several hours: magnesium hydride needs to be heated up to more than 300 C to reach appropriate sorption kinetics. [1±4] Many attempts have been made to qualify magnesium hydride for such uses by improving its the absorption and desorption behavior. Recently, a breakthrough was achieved by preparing nanocrystalline hydrides using highenergy ball milling. [5±12] Nanocrystalline magnesium hydride has fast absorption kinetics with a loading time of few minutes at 300 C. However, desorption (as well as absorption at lower temperatures) is still a problem. [13] The difficulty with absorption is due to the poor dissociation ability of metallic Mg for hydrogen molecules, because the probability of the adsorption of a H 2 -molecule on the Mg surface is 10 ±6 . [14] To overcome this, catalysts have to be added to magnesium. As has been shown, Pd, Ni, and Fe can be used to improve H 2 dissociation at the surface in Mg 2 Ni, FeTi, or LaNi 5 . [2,15±18] Tanguy et al. have demonstrated that for microcrystalline magnesium the addition of V or Ti also causes a catalytic acceleration of hydrogen absorption. [19] Recently, the effect of transition metals (Ti, V, Mn, Fe, Ni) on nanocrystalline Mg was investigated by Liang et al. [20,21] They showed that ballmilled MgH 2 with 5 at.-% transition metal absorbs hydrogen at room temperature (1 MPa) and desorbs at 235 C (0.015 MPa). In our previous studies the advantages of using cheap metal oxides as catalysts have been reported. [22] Even a metal-oxide content as low as 0.2 mol.-% is effective, which leads to a high storage capacity and to a more cost-effective storage material. In this communication results for MgH 2 with different oxide catalysts are compared (metal oxide = Sc Special emphasis is put on the sorption kinetics at reduced temperatures, from 300 C down to room temperature. Figure 1 and Figure 2 show that the addition of 0.2 mol.-% Cr 2 O 3 leads to better hydrogen absorption and desorption at 300 C than for pure magnesium hydride. For Cr 2 O 3 , 0.2 mol.-% corresponds to 0.3 vol.-% or 1 wt.-%. Full release of hydrogen is possible within a few minutes under the experimental conditions. The desorption rates (the slope of the desorption curve between 80 and 20 % of its maximum capacity) of the different MgH 2 /Me x O y systems vary between 4 and 40 kW/kg. While the addition of CuO, Al 2 O 3 , Sc 2 O 3 , or SiO 2 causes only a little change in the desorption rate compared with nano...

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Metal oxides as catalysts for improved hydrogen sorption in nanocrystalline Mg-based materials

Cited by 747 publications

References 24 publications

Probing the highly efficient room temperature ammonia gas sensing properties of a luminescent ZnO nanowire array prepared via an AAO-assisted template route

Probing the highly efficient room temperature ammonia gas sensing properties of a luminescent ZnO nanowire array prepared via an AAO-assisted template route

Effect of Alloying Elements in Melt Spun Mg-alloys for Hydrogen Storage

Hydrogen Sorption of Nanocrystalline Mg at Reduced Temperatures by Metal-Oxide Catalysts

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