First-Principles Molecular Dynamics Simulations of Indium Oxide/Water Interfaces.*

Indium oxide (In₂O₃) is commonly used as a transparent conducting electrode in  photovoltaic and electrochemical cells, due to its high photocatalytic activity, chemical stability, and commercial availability. In particular, indium oxide surfaces in contact with water can produce hydroxyl radicals (•OH) from the splitting of interfacial water molecules, which are required for advanced oxidation processes. In order to optimize desired oxidation processes, it is important to understand the influence of surface hydroxylation, doping (e.g. with tin) and disorder in determining the properties of the interface with water and the ability of the solid oxide to induce water splitting. Here, we carry out first principles molecular dynamics simulations with the SCAN functional and the Qbox code to study indium oxide/water interfaces under different hydroxyl coverages (100%, 98%, 83% and 66% hydroxylation), with the goal of characterizing the structural, electronic, and vibrational properties of the aqueous interface. In particular, computed IR and Raman spectra provide unique insight into hydrogen bonding and dissociation at the interface. Work is in progress to carry out a detailed comparison between simulations and experiments.