Carbon-modified MgH2: Experimental and ab-initio Investigations

The results of experimental and theoretical investigations of carbon-modified MgH2 for improving its sorption performances in hydrogen storage devices are reported. Large changes on its absorption/desorption capacities have been found. The following aspects are considered: size effects where finer particles obtained by energetic ball milling enable easier penetration, catalytic effects of carbon at the surface, and entrance of small quantities of C interstitially into the MgH2 structure. The energies and charge densities as studied by DFT suggest the activation of MgH2 through a decrease of the cohesive energy of the pristine hydride and a reduced ionic charge on hydrogen.