Atomic Structure of Water Monolayer on Anatase TiO2(101) Surface

The molecular structure and interactions of interfacial water, i.e., the first monolayers of water adsorbed on surfaces, are critical to determine the microscopic properties of solid–liquid interfaces. In particular, interfacial water on TiO2 anatase (101) is of specific relevance to industrial, environmental, and medical applications. However, owing to the complexity and challenges in sample preparation, direct observation has been limited to individual or short-range ordered water molecules adsorbed on anatase. In this article, we report the direct observation of an unprecedented long-range ordered water monolayer on TiO2 anatase (101). The adsorption structure and inter/intramolecular interactions of the water molecules have been investigated using scanning tunneling microscopy (STM) at 5 K in conjunction with density functional theory calculations. Additionally, the effect of STM tip-induced electric field was calculated to elucidate the ground-state structure of the water monolayer. The water molecul...