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Kinetic Enhancement of Direct Hydrogenation of MgB 2 to Mg(BH 4 ) 2 upon Mechanical Milling with THF, MgH 2 , and/or Mg

2019; Wiley; Volume: 20; Issue: 10 Linguagem: Inglês

10.1002/cphc.201801187

1439-7641

Cody Sugai, Stephen Kim, Godwin Severa, J. L. White, Noémi Leick, Madison B. Martinez, Thomas Gennett, Vitalie Stavila, Craig M. Jensen,

Boron and Carbon Nanomaterials Research

Abstract Modification of magnesium diboride, MgB 2 , by mechanical milling with THF, MgH 2 , and/or Mg results in a lowering of the conditions required for its direct, bulk hydrogenation to magnesium borohydride, Mg(BH 4 ) 2 , by 300 bar and 100 °C. Following mechanical milling with MgH 2 or THF and Mg, MgB 2 can be hydrogenated to Mg(BH 4 ) 2 at 300 °C under 700 bar of H 2 while achieving ∼54–71 % conversion to the borohydride. The discovery of a means of dramatically lowering the conditions required for the hydrogenation of MgB 2 is an important step towards the development of a practical onboard hydrogen storage system based on hydrogen cycling between Mg(BH 4 ) 2 and MgB 2 . We suggest that mechano‐milling with THF, Mg, and/or MgH 2 may possibly introduce defects in the MgB 2 structure which enhance hydrogenation. The ability to activate the MgB 2 through the introduction of structural defects transcends its relevance to hydrogen storage, as a method of overcoming its chemical inertness provides the key to harnessing other interesting properties of this material.