Defect-Induced Wetting Behavior on Solid Polar Surfaces with Small Charge Dipole Length

Previous work showed that solid polar surfaces with a very small dipole length still might be quite hydrophobic even with large values of charge. Using molecular dynamics simulations, we have found that the presence of the point defects on a solid polar surface greatly influences the wetting behavior of water, even at a very low defect ratio of 1%. As the defect ratio increases, the coverage of the water layer over the solid surface also increases. Because of the breakdown of steric exclusion, the water molecules strongly bind to the solid surface mainly through electrostatic interactions between their hydrogen atoms and the negative charges near the positive-vacancy defects on the surface, or between their oxygen atoms and the positive charges near the negative-vacancy defects.