DFT Simulation on Interaction of H2O Molecules with ZnS and Cu-Activated Surfaces

The adsorption of isolated, monolayer, and multilayer water molecules on ZnS and Cu-activated surfaces was studied by density functional theory (DFT) calculations. Adsorption energy calculation and adsorption configuration analysis of water molecules suggest that the ZnS surface is more hydrophilic than the Cu-activated surface. It is found that both metal-O interaction and OH center dot center dot center dot S hydrogen-bond interaction on the ZnS surface are greater than those on the Cu-activated surface. In addition, the difference in the adsorption of water molecules is related to the difference in the surface structure of ZnS and Cu-activated surfaces. Density-of-state (DOS) calculation suggests that Cu-activated surface has stronger pi-bond and covalency than ZnS surface. The DOS calculation also suggests that the electronic interaction of H and S atoms on the ZnS surface is stronger than that on the Cu-activated surface. Dynamics simulations using density functional based tight binding method suggest that the water molecules close to the mineral surfaces are arranged in order.