Novel Mechanism for the Dissociation of H2O and the Diffusion of O and H along the aAl2O3 (0001) Surface

Based on density functional theory - generalized gradient approximation calculations (DFT-GGA), we provide a theoretical model for the effect of the catalytic support (alphaAl₂O₃) on the dissociation of H₂O and the surface diffusion of oxygen and hydrogen species along the alphaAl₂O₃ surface. Our results indicate that upon interaction with the surface, water spontaneously dissociates, forming hydroxyls with unsaturated surface Al and neighboring oxygen atoms. In addition, we find that oxygen species can easily diffuse locally but there is a large barrier to long range surface diffusion in the absence of defects or other species. In contrast, the barrier to the long range surface diffusion of hydrogen is modest under ideal conditions.