Theoretical study of hydrogen permeation through mixed NiO-MgO films supported on Mo(100): role of the oxide-metal interface.
This work presents a periodic density functional study of the adsorption and permeation of atomic H on Ni-doped MgO oxide thin films supported on a Mo(100) surface. We find that the binding of atomic H is affected by the presence of a metallic support. The chemisorption energies increase considerably when the oxide film is supported. The H permeation through the NiO-MgO oxide was also studied. H migration through the unsupported NiO-MgO oxide is thermodynamically inhibited, while the presence of the metallic Mo makes permeation thermodynamically favored. We attribute the promoting effect to the different character of adsorbed H at the unsupported Ni-doped MgO oxide and at the oxide-Mo interface. In the former case, H forms hydroxyl groups, whereas in the latter case it appears as hydride due to the formation of strong metal-hydrogen bonds. These results illustrate the important role that the oxide-metal interface could play in the mechanism for pure and mixed oxides reduction.
Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Daniel
D
Torres
Francesc
F
Illas
Ping
P
Liu