The synthesis and hydrogen storage properties of a MgH_2 incorporated carbon aerogel scaffold

A new approach to the incorporation of MgH_2 in the nanometer-sized pores of a carbon aerogel scaffold was developed, by infiltrating the aerogel with a solution of dibutylmagnesium (MgBu_2) precursor, and then hydrogenating the incorporated MgBu_2 to MgH_2. The resulting impregnated material showed broad x-ray diffraction peaks of MgH_2. The incorporated MgH_2 was not visible using a transmission electron microscope, which indicated that the incorporated hydride was nanosized and confined in the nanoporous structure of the aerogel. The loading of MgH_2 was determined as 15–17 wt%, of which 75% is reversible over ten cycles. Incorporated MgH_2 had >5 times faster dehydrogenation kinetics than ball-milled activated MgH2, which may be attributed to the particle size of the former being smaller than that of the latter. Cycling tests of the incorporated MgH_2 showed that the dehydrogenation kinetics are unchanged over four cycles. Our results demonstrate that confinement of metal hydride materials in a nanoporous scaffold is an efficient way to avoid aggregation and improve cycling kinetics for hydrogen storage materials.