Mg@C60 nano-lamellae and its 12.50 wt% hydrogen storage capacity

Abstract

The design and synthesis of new hydrogen storage materials with high capacity are the prerequisite for extensive hydrogen energy application which can be achieved by multi-site hydrogen storage. Herein, a Mg@C60 nano-lamellae structure with multiple hydrogen storage sites has been prepared through a simple ball-milling process in which Mg nanoparticles (∼5 nm) are homogeneously dispersed on C60 nano-lamellae. The as-obtained C60/Mg nano-lamellae displays an excess hydrogen uptake of 12.50 wt% at 45 bar, which is far higher than the theoretical value (7.60 wt%) of metal Mg and the US Department of Energy (DOE) target (5.50 wt%, 2020 year), also the experimental values reported by now. The enhanced hydrogen storage mainly comes from several storage sites: MgH2, Hx–C60 (CH chemical bonding), H2@C60 (the endohedral H2 in C60). Interestingly, the hybridization of Mg and C60 not only facilitate the dissociation of H2 molecules to form CH bonding with C60, but also promote the deformation of C60 and access H2 molecules into the cavity of C60. This work provides new insight into the underlying chemistry behind the high hydrogen storage capacities of a new class of hydrogen storage materials, fullerene/alkaline-earth metals nanocomposites.