Comparative study of the structure and dynamics of water confined between nickel nanosheets and bulk water, a study using reactive force fields

In this study, the structure and dynamics of water molecules confined between nickel surfaces and its comparison with water in bulk are investigated. To this end, molecular dynamics approach accompanied by reactive force field is used to study the characteristics of the confined water. The results showed that water molecules near the enclosing surfaces change in terms of structure and dynamics. The water molecules form a two-layer structure close to the nickel surface, and the results of the partial charge distribution give an electric double layer at the interface, with a positive partial charge of nickel atoms at surface against the negative partial charge of the first layer of water molecules. In addition, intense stratification effects near the nickel surfaces are visible. The radial distribution functions showed that, on average, the hydrogen atoms of the water molecules in the near-surface layers are closer to the nickel than the oxygen atoms, and also because of the repulsive effects induced by the interaction with the surfaces, water molecules would be found at distances further than 2 A. Different orientations of the water molecules relative to the nickel surface were calculated using orientational ordering. This calculation shows the character of heterogeneous water molecules in confined state. (C) 2019 Elsevier B.V. All rights reserved.