γ-MgH2 induced by high pressure for low temperature dehydrogenation

Zhaoyue Weng, Ilizel Retita, Yu Sheng Tseng, Andrew J. Berry, Dean R. Scott, Daniel Leung, Yu Wang, S. L.I. Chan

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The formation of metastable γ-MgH2 upon application of ultra-high pressure and its dehydrogenation properties were studied. Magnesium-nickel alloy (14 wt.% Ni) was hydrogenated and compressed at ultra-high pressures of 2.5 and 4 GPa. The phase composition and desorption properties of the products were investigated. Powder X-ray diffraction indicated that some α-MgH2 converted to γ-MgH2 during compression. This resulted in the onset of hydrogen desorption at 60 °C under vacuum. Our findings thus show that application of ultra-high pressure can facilitate the formation of γ-MgH2, which has a lower dehydrogenation temperature (≤200 °C) than α-MgH2, which desorbs at temperatures above 300 °C. The metastable phase possessed a high hydrogen storage capacity of at least 4.5 wt.%. These properties revealed the potential of γ-MgH2 as a future hydrogen storage material.

Original languageEnglish
Pages (from-to)5441-5448
Number of pages8
JournalInternational Journal of Hydrogen Energy
Volume46
Issue number7
DOIs
StatePublished - 27 Jan 2021

Keywords

  • Crystal structure
  • High pressure
  • Hydrogen storage
  • Magnesium alloys
  • Phase transformations

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