Effect of a Ti-Based Additive on the Desorption in Isotope-Labeled LiB(H,D)4–Mg(H,D)2 Nanocomposites

The desorption behavior of LiBH4-MgH2 nanocomposites with and without titanium isopropoxide additive has been investigated with samples where hydrogen was partly replaced by deuterium. FT-IR spectrometry indicates that almost no hydrogen exchange between the two hydrides occurs during synthesis of the nanocomposites by high energy ball-milling. Thermal analyses together with the identification of the evolved gas species show a significant isotope scrambling once the desorption process has started. A majority of D-2 gas species releases from the 2LiBD(4)-MgH2 nanocomposite while 2LiBH(4)-MgD2 emits predominantly HD. Additions of low concentration titanium isopropoxide lower the desorption temperatures but do not affect the desorption sequence. The occurrence of hydrogen exchange during desorption is discussed in terms of hydrogen motion which takes place either at the LiBH4/MgH2 interface or in the molten LiBH4 layer.