Acceleration of aqueous nano-film evaporation by applying parallel electric field: A molecular dynamics simulation

Abstract

In this work, molecular dynamics simulation has been applied to investigate the influence of external electric field on the evaporation of the aqueous nano-film. The evaporation of the aqueous nano-film with 2240 water molecules and 50 NaCl on a gold (1 0 0) surface is analyzed at the electric fields with various intensities (0, 0.05, 0.1, 0.2 and 0.3 V nm−1) and directions. The predictions show that the evaporation of aqueous film is remarkably enhanced when the electric field Ex = 0.2 or 0.3 V nm−1 is parallel to the aqueous film surface. It is also noted that free ions in the aqueous film are accelerated under the action of the higher Ex and water molecules in the hydration shell move together with the ions due to the hydration effect. As a result, the interaction between water molecules decreases, which is responsible for increasing the evaporation of the aqueous film under the action of the higher Ex. While applying the electric field Ey = ±0.3 V nm−1 perpendicular to the aqueous film, ions cannot be in accelerated motion due to the existence of a solid-liquid interface and a liquid-gas surface in y-direction. Therefore, the evaporation enhancement is much lower than that of the aqueous film under the action of the Ex.