A DFT study of hydrogen storage on surface (110) of Mg_1−xAl_x (0 ≤ x ≤ 0.1)

One difficult aspect to be overcome within technology of hydrogen and fuel cells is hydrogen storage in solid phase materials. Theoretical studies are indispensable support to guide the experimentalist in the development of synthesis or characterization of new materials. DFT (density functional theory) was used to optimize the geometry, and at same time, to obtain final enthalpy of bulk alloys of Mg_1−xAl_x (0 ≤ x ≤ 0.10) and later it was possible to cleave bulk alloy in the direction of the plane (110) to obtain surface effects. Finally, hydrogen molecules were added at the surface of MgAl in the direction (110) and optimized their geometry in order to obtain their final enthalpies of each one of these alloys. Values of chemisorption energy and repulsion of those alloys were obtained, as well as aluminum optimum concentration for adsorption of hydrogen. The value of binding energy for H₂ molecule on magnesium surface is about 0.5 eV.