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

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 E _x = 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 E _x 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 E _x . While applying the electric field E _y = ±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 E _x .