The synthesis and hydrogen storage properties of aMgH2 incorporated carbon aerogel scaffold

Abstract

A new approach to the incorporation ofMgH2 in the nanometer-sized pores of a carbon aerogel scaffold was developed,by infiltrating the aerogel with a solution of dibutylmagnesium (MgBu2) precursor, and then hydrogenating the incorporatedMgBu2 toMgH2. The resulting impregnated material showed broad x-ray diffraction peaks ofMgH2. Theincorporated MgH2 was not visible using a transmission electron microscope, which indicated that the incorporatedhydride was nanosized and confined in the nanoporous structure of the aerogel. The loading ofMgH2 was determined as 15–17 wt%, of which 75% is reversible over ten cycles. IncorporatedMgH2 had>5 times faster dehydrogenation kinetics than ball-milled activatedMgH2, which may be attributed to the particle size of the former beingsmaller than that of the latter. Cycling tests of the incorporatedMgH2 showed that the dehydrogenation kinetics are unchanged over four cycles. Our resultsdemonstrate that confinement of metal hydride materials in a nanoporous scaffold is anefficient way to avoid aggregation and improve cycling kinetics for hydrogen storagematerials.