Water Breakup at Fe₂O₃-Hematite/Water Interfaces: Influence of External Electric Fields from Nonequilibrium Ab Initio...

The dynamical properties of physically and chemically adsorbed water molecules at pristine hematite-(001) surfaces have been studied by means of nonequilibrium ab initio molecular dynamics (NE-AIMD) in the NVT ensemble at room temperature, in the presence of externally applied, uniform static electric fields of increasing intensity. The dissociation of water molecules to form chemically adsorbed species was scrutinized, in addition to charge redistribution and Grotthus proton hopping between water molecules. Dynamical properties of the adsorbed water molecules and OH^- and H₃O⁺ ions were gauged, such as the hydrogen bonds between protons in water molecules and the bridging oxygen atoms at the hematite surface, as well as the interactions between oxygen atoms in adsorbed water molecules and iron atoms at the hematite surface. The development of Helmholtz charge layers via water breakup at Fe₂O₃-hematite/water interfaces is also an interesting feature, with the development of protonic conduction on the surface and more bulk-like water.