Proton Migration on Perfect, Vacant, and Doped MgO(001) Surfaces: Role of Dissociation Residual Groups

Abstract

Although migration processes on low-coordination surface sites of a magnesium oxide (MgO) surface are important in technological applications including catalysis in gas interfaces, they are not well understood. In particular, hydrated MgO(001) surfaces present charge transfer and ionic transport phenomena that sometimes do not work properly in technological devices. On the other hand, low-coordination surface sites are chemically attractive. Given that defects and adsorbed species can be characterized by the kinetics of surface processes, in this work, we investigated proton mobility pathways produced from the dissociative adsorption of water molecules on different MgO(001) surfaces: a perfect-terrace, with an anionic vacancy, and with an Al-doped + cationic vacancy. For that purpose, we employed density-functional theory with periodic boundary conditions combined with the climbing imaged nudged elastic band method to compute energy barriers. The dissociative adsorption of water molecules on the perfect-t...