Examining the effect of flake orientation on the hydrophilicity of MoS2 by molecular simulations

Abstract

The interaction of molybdenum disulfide (MoS2) with water and consequently the surface wettability are important to understand to efficiently use this layered material in semiconductor and lubricant applications. Using molecular dynamics simulations, we investigate the coupled effect of flake orientation (0° and 90°) and temperatures (300 K and 400 K) on the wettability of MoS2. Our results reveal that the horizontally oriented MoS2 is relatively less hydrophilic than the vertically oriented MoS2 due to the difference in the flake-orientation driven atomic interactions. An increase in temperature (≥400 K) transforms the horizontally oriented MoS2 to a relatively hydrophobic surface, while retaining the hydrophilicity in the vertically oriented flakes due to the bond anisotropy in the material, which impacts the surface free energy.