Superior catalytic effect of nanocrystalline big-cube Zr2Ni metastable phase for improving the hydrogen sorption/desorption kinetics and cyclability of MgH2 powders

M. Sherif El-Eskandarany, H. Al-Matrouk, Ehab Shaban and Ahmed Al-Duweesh

Energy, 2015, vol. 91, issue C, 274-282

Abstract: Reactive ball milling was employed to synthesize nanocrystalline MgH2 powders using a high-energy ball milling of pure Mg powders under 50 bar of a hydrogen gas atmosphere. The end-product of MgH2 powders obtained after 200 h of a continuous reactive ball milling time composed of fine grains (∼7 nm in diameter) of γ and β phases. A new catalytic agent of big-cube Zr2Ni nanocrystalline phase, which is proposed in the present study for improving the hydrogenation/dehydrogenation kinetics of MgH2 powders, was obtained upon high-energy ball milling of tetragonal-Zr2Ni powders for 150 h. The as-ball milled Zr2Ni powders consisted of ultrafine grains with an average grain size of 6 nm in diameter. The as-prepared MgH2 powders were mechanically doped with 10 wt% of big-cube Zr2Ni powders for 50 h, using high-energy ball mill under a hydrogen gas atmosphere for 50 h. The powders obtained after 50 h of milling enjoyed homogeneous morphology and uniform composition close to the starting nominal composition. Moreover, this binary nanocomposite system possessed superior hydrogenation/dehydrogenation kinetics at 250 °C, as suggested by the short time required to absorb and desorb 5.1 wt% H2 within 100 s and 613 s, respectively. At this temperature, the synthesized nanocomposite powders possessed excellent absorption/desorption cyclability of 2546 complete cycles within 1250 h. However, a minor degradation (∼0.5 wt% H2) in the hydrogen storage capacity was observed between 300 h and 2546 h of the cycle-life-time. This slight degradation took place due to the grain growth came off in the Mg/Zr2Ni grains.

Keywords: Reactive ball milling; Mechanical milling; Metal hydrides; Zr alloys; Hydrogenation/dehydrogenation; Cycle-life-time (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0360544215011305
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:91:y:2015:i:c:p:274-282

DOI: 10.1016/j.energy.2015.07.135

Access Statistics for this article

Energy is currently edited by Henrik Lund and Mark J. Kaiser

More articles in Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().