▎ 摘　　要

In this paper the adsorption behavior of a water droplet on the molybdenum disulfide and graphene surfaces were examined and compared. Results obtained from the calculation of the average of interaction energy between the water and the molybdenum disulfide surface and the graphene surfaces indicated that the van der Waals interaction plays an important role in the adsorption of water on these surfaces. The contour maps of the interaction energy between the water and the surfaces have revealed some different behaviors of the water droplet on these surfaces. The results showed that water sliding on the molybdenum disulfide surface and water pinning on the graphene surface is due to the difference in structural patterns of the surfaces. Molecular investigations of the water on the surfaces showed that the water molecules occupy continues positions on the molybdenum disulfide surface while they occupy discrete positions on the graphene surface. Two mechanisms for orientation and displacement of the water molecules on the surfaces were proposed. In addition, the effects of temperature and external field on movement of the water molecules on the surface were investigated. It was observed that the water - graphene system is more sensitive to the applied electric field than water-molybdenum disulfide system. In addition, the simulation results in the presence of the electric field showed that it is possible to take control of the water droplet on the graphite surface, so that the displacement of the water droplet can take place in a particular direction. (C) 2016 Elsevier B.V. All rights reserved.