Co-adsorption of O-2 and H2O on Al(111) surface: a vdW-DFT study

摘要

Using first-principles calculations based on van der Waals density functional theory, we systematically studied the co-adsorption behavior of H2O and O-2 on Al(111) surfaces. The study consists of two parts: (i) the adsorption of H2O molecules on O pre-adsorbed Al(111) surfaces, and (ii) co-adsorption of H2O and O-2 molecules on a clean Al(111) surface. H2O adsorbs on O pre-adsorbed Al(111) surfaces in the form of a molecule, while both the adsorption energies and partial density states results prove that the adsorption of H2O is strengthened with the increasing pre-adsorbed O coverage. An Al atom bonded with H2O is pulled out of the surface in all adsorbed structures because of the repulsion between pre-adsorbed O atoms and the O atoms of H2O. For the co-adsorption of H2O and O-2 on a clean Al(111) surface, H2O molecules can dissociate into OH and H when both of the two O atoms of O-2 can interact with H atoms of H2O, or else they will adsorb on the surface keeping the behavior of single adsorption. For the dissociation adsorption of H2O, the redistribution of charge occurs and the value of charge transfer from the surface and O-2 to H2O is much larger than that of molecular adsorption, which is larger than 0.1.