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

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@C-60 nano-lamellae structure with multiple hydrogen storage sites has been prepared through a simple ball-milling process in which Mg nanoparticles (similar to 5 nm) are homogeneously dispersed on C-60 nano-lamellae. The as-obtained C-60/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, H-x-C-60 (C-H chemical bonding), H-2@C-60 (the endohedral H-2 in C-60). Interestingly, the hybridization of Mg and C-60 not only facilitate the dissociation of H-2 molecules to form C-H bonding with C-60, but also promote the deformation of C-60 and access H-2 molecules into the cavity of C-60. 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. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.