Dissociation and reconstruction of O2 on Al (1 1 1) studied by First-principles

The dissociative adsorption and reconstruction of oxygen molecule on Al (1 1 1) surface have been investigated by Density Functional Theory (DFT) with the generalized gradient approximation using structure optimization and a supercell approach. Four vertical and eight parallel sites of O2 adsorption on Al (1 1 1) surface were calculated corresponding to oxygen coverages of 0.22, 0.5 and 1 ML (monolayer). It is found that different surface geometries are formed after oxygen molecule dissociation on different sites of Al (1 1 1) surface, which is determined by oxygen original adsorption sites as well as oxygen coverage. The oxygen atoms coming from oxygen molecule dissociation tend to occupy the most stable adsorption sites of the Al (1 1 1) surface. When oxygen coverage is 1 ML, the dissociation of oxygen molecule is related to both its original adsorption site and the interaction between oxygen molecules. The correlation of surface reconstruction of Al (1 1 1) surface, adsorption site, adsorption energy and oxygen coverage is discussed in detail. The steering effect plays an important role in the oxygen molecule dissociative process.