Impact of Atomic\nDefects on Water Contact Angle of\n2D Molybdenum Disulfide Surfaces

Interfacial dynamics within nanofluidic systems are crucial\nfor\napplications like water desalination and osmotic energy harvesting.\nUnderstanding these dynamics can inform the rational optimization\nof two-dimensional (2D) materials and devices for such applications.\nThis study explores the wetting behavior of realistic 2D MoS<sub>2</sub> surfaces incorporating vacancies and atomic steps, known as atomic\ndefects. We employ a combined density functional theory (DFT) and\nmolecular dynamics (MD) computational approach to elucidate the influence\nof atomic defects on the MoS<sub>2</sub>-water interface. DFT calculations\nare utilized to determine the charge distribution within MoS<sub>2</sub>. Subsequently, free energy calculations are obtained through MD\nsimulations of the MoS<sub>2</sub>-water interface. Our findings underscore\nthe importance of incorporating atomic defects into MoS<sub>2</sub> surfaces for accurate water contact angle (WCA) predictions in nanofluidic\nsimulations, particularly when using Abal et al. force field parameters.\nHowever, the force field developed by Liu et al. yielded more accurate\nresults for pristine MoS<sub>2</sub> surfaces. While these parameters\nprovide reliable outcomes for pristine MoS<sub>2</sub> surfaces, their\napplication to surfaces with defects may lead to underestimation of\nWCA. This highlights the critical need for realistic surface representations\nin nanofluidic modeling to accurately capture the complex interactions\nbetween water and MoS<sub>2</sub> materials.