MgH2 with different morphologies synthesized by thermal hydrogenolysis method for enhanced hydrogen sorption

Magnesium hydride (MgH2) with a range of morphologies has been synthesized via a simple hydrogenolysis route involving the decomposition of di-n-butylmagnesium. As the synthetic medium evolved from an inert atmosphere of argon to hydrogen pressure, the morphology shifted from rod like to small particles (25–170 nm). In cyclohexane, a solvent relative inert toward magnesium, smaller particles (15–50 nm) were formed. However in diethyl ether, which is more reactive toward magnesium, flakes organized in large microstructures were obtained. Remarkably in all cases β-MgH2 was readily obtained with some residual carbon contamination. Hydrogen release from these structures occurred at a relatively low temperature (300 °C), with desorption kinetics faster or equivalent to that of ball milled magnesium. In particular, hydrogen desorption from the smallest particles of MgH2 produced via the hydrogenolysis of di-n-butylmagnesium under hydrogen pressure or cyclohexane was impressive with the full desorption achieved in less than 10 min without any catalyst. These remarkable hydrogen storage properties are believed to result from an appropriate stabilization of the nanoparticles generated.

► MgH2 can be readily formed via the hydrogenolysis of di-n-butylmagnesium.
► The size/morphology of the MgH2 particles depend upon the synthetic medium.
► This provides a tool for modifying the hydrogen sorption properties of the materials.
►  Hydrogen sorption kinetics far superior to that of ball milled magnesium were obtained.