Delaminated MoS2 as a structural and functional modifier for MgH2 – Better hydrogen desorption kinetics through induced worm-like morphologies

Abstract

Magnesium hydride (MgH2) nanoparticles have been synthesized in the presence of MoS2 via a simple hydrogenolysis route, involving the decomposition of di-n-butylmagnesium. Remarkably using delaminated MoS2 instead of bulk MoS2 led to the formation of magnesium worm-like structures, which collapsed and recrystallized to some extent upon hydrogen cycling. Hydrogen release from these structures occurred at a relatively low temperature (300 °C), and MoS2 was found to effectively improve the hydrogen desorption kinetics of nanosized MgH2. It took less than 150 min to fully release hydrogen from MgH2 catalyzed by delaminated MoS2. In comparison, uncatalysed nanosized MgH2 particles required more than 300 min. Furthermore, MoS2 was found to significantly influence the thermodynamic properties of the Mg/MgH2 reaction, via the destabilization of the Mg–H bond. Compared to ball-milled MgH2, the MoS2 modified materials showed significantly higher hydrogen absorption plateau pressures (∼0.15 MPa). This demonstrates that pathways enabling the tuning of the hydrogen storage properties of nanosized MgH2 toward lower temperatures and fast kinetics may exist.