Adsorption of atomic and molecular hydrogen on 2-D AlN nanostructure

Employing density functional calculations including an empirical dispersion term, we investigated thehydrogenation of an aluminum nitride nanosheet (h-AlN) with atomic and molecular hydrogen. It was found that atomicH prefers to be adsorbed on an N atom rather than Al, releasing energy of 21.1 kcal/mol. The HOMO/LUMO energy gapof the sheet is dramatically reduced from 4.68 to 1.93 eV upon the adsorption of one hydrogen atom. The adsorption ofatomic H on the h-AlN presents properties which are promising for nanoelectronic applications. The molecular H2 wasfound to be adsorbed collinearly on an N atom and dissociated to two H atoms on Al-N bond. Calculated barrier andadsorption energies for this dissociation process are about 18.9 and 1.9 kcal/mol. We predict that each nitrogen atom inan AlN sheet can adsorb two hydrogen molecules on opposite sides of the sheet, and thus the gravimetric density forhydrogen storage on AlN sheet is evaluated to be about 8.9 wt %.

Adsorption of atomic and molecular hydrogen on 2-D AlN nanostructure Keywords:

DFT , Hydrogen storage , Aluminum nitride , Nanostructures