材料期刊网

The hydrogen storage properties on a single nano-scale AlN sheet with and without an applied electric field are investigated by using first-principles method based on density functional theory. The H-2 molecule on top of a N atom is the most stable adsorption state, while the H-2 molecule on top of an Al atom is a metastable one in the absence of an applied electric field. The diffusion barrier of the H-2 molecule from the metastable state to the most stable state is about 0.002 eV, which can be easily overcome in experiments. It is found that two layers of H-2 molecules can be steadily adsorbed on and below (upper H-2 molecules on the N atoms and lower H-2 molecules on the Al atoms) the sheet, respectively, by applying a suitable electric field. The reliability of H-2 adsorption on the AlN sheet is evaluated by investigating the changes of H-2 adsorption energy, bond lengths, and density of states. The stored H-2 molecules can be controllably released by reducing the strength of the applied electric field, thus making reversible hydrogen storage on the AlN sheet.