Sodium Halide Adsorption and Water Structure at the α-Alumina(0001)/Water Interface

Abstract

Alumina is one of the most abundant minerals and has a wide range of industrial applications, with catalysis as one of the most important. Of particular relevance for catalysis is the structure of the mineral/water interface. In this work, water structure and sodium halide adsorption at the neutral α-alumina(0001)/water interface are investigated using molecular dynamics simulations. This work demonstrates the accuracy of the chosen model of the alumina/water interface and shows that high charge density monovalent ions, such as Na+ and F–, have a strong affinity for the interface due to the specific pattern of alumina surface OH groups, such that the adsorbed ions displace waters that are hydrogen-bonded to the surface in their absence. A significant portion of the driving force for anion adsorption arises from surface bound Na+, which reverse the intrinsic surface dipole field and drive the accumulation of halides at the interface. The resulting electrolytic interfacial structure reorients water molecule...