Atomic-Scale Characterization of Interfacial Water on LaTiO ₂ N(100) Surface

Perovskite oxynitride LaTiO 2 N holds promise for visible-light-driven photocatalytic water splitting, yet its surface dynamics at the catalyst-water interface remain elusive. This study employs state-of-the-art density functional theory molecular dynamics (DFT-MD) and electrochemical measurements to unravel the intricate interplay of water arrangement and adsorption on the LaTiO 2 N(100) surface. By considering explicit solvent effects, we reveal a pronounced hydrophilic character, with spontaneous water dissociation forming hydroxyl groups at undercoordinated Ti sites at the surface, stabilizing the latter and potentially enhancing the OER activity. Our simulations identify the thermodynamically stable termination and demonstrate its role in fostering robust hydrogen-bond networks that facilitate proton-coupled electron transfer. The surface Pourbaix diagram underscores hydroxylated configurations across diverse electrochemical conditions, corroborated by DFT-MD insights. These findings highlight the critical role of treating an explicit solvent environment and its dynamics at a given temperature in the modeling of LaTiO 2 N, offering a blueprint for designing high-performance, sustainable water-splitting catalysts.