Impact of Atomic Defects on Water Contact Angle of 2D Molybdenum Disulfide Surfaces

Interfacial dynamics within nanofluidic systems are crucial for applications like water desalination and osmotic energy harvesting. Understanding these dynamics can inform the rational optimization of two-dimensional (2D) materials and devices for such applications. This study explores the wetting behavior of realistic 2D MoS₂ surfaces incorporating vacancies and atomic steps, known as atomic defects. We employ a combined density functional theory (DFT) and molecular dynamics (MD) computational approach to elucidate the influence of atomic defects on the MoS₂-water interface. DFT calculations are utilized to determine the charge distribution within MoS₂. Subsequently, free energy calculations are obtained through MD simulations of the MoS₂-water interface. Our findings underscore the importance of incorporating atomic defects into MoS₂ surfaces for accurate water contact angle (WCA) predictions in nanofluidic simulations, particularly when using Abal et al. force field parameters. However, the force field developed by Liu et al. yielded more accurate results for pristine MoS₂ surfaces. While these parameters provide reliable outcomes for pristine MoS₂ surfaces, their application to surfaces with defects may lead to underestimation of WCA. This highlights the critical need for realistic surface representations in nanofluidic modeling to accurately capture the complex interactions between water and MoS₂ materials.