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Reversible Hydrogen Storage by a Li–Al–N–H Complex
Author(s) -
Xiong Z.,
Wu G.,
Hu J.,
Liu Y.,
Chen P.,
Luo W.,
Wang J.
Publication year - 2007
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200600759
Subject(s) - octahedron , hydrogen storage , materials science , ball mill , hydrogen , molar ratio , crystallography , fourier transform infrared spectroscopy , diffraction , analytical chemistry (journal) , crystal structure , chemical engineering , metallurgy , chemistry , alloy , catalysis , biochemistry , physics , organic chemistry , optics , chromatography , engineering
Stepwise solid‐state reaction between LiNH 2 and LiAlH 4 at a molar ratio of 2:1 is investigated in this paper. It is observed that approximately four H atoms are evolved from a mixture of LiNH 2 –LiAlH 4 (2:1) after mechanical ball milling. The transformation of tetrahedral [AlH 4 ] – in LiAlH 4 to the octahedral [AlH 6 ] 3– in Li 3 AlH 6 is observed after ball milling LiAlH 4 with LiNH 2 . Al–N bonding is identified by using solid‐state 27 Al nuclear magnetic resonance (NMR) measurements. The NMR data, together with the results of X‐ray diffraction and Fourier transform IR measurements, indicate that a Li–Al–N–H intermediate with the chemical composition of Li 3 AlN 2 H 4 forms after ball milling. Heating the post‐milled sample to 500 °C results in the liberation of an additional four H atoms and the formation of Li 3 AlN 2 . More than 5 wt % hydrogen can be reversibly stored by Li 3 AlN 2 . The hydrogenated sample contains LiNH 2 , LiH, and AlN. The role of AlN in the reversible hydrogen storage over Li–Al–N–H is discussed.