Comparison of Multilayer Water Adsorption on the Hydrophobic Galena (PbS) and Hydrophilic Pyrite (FeS2) Surfaces: A DFT Study

Abstract

To investigate the essential difference in the water adsorption on the hydrophobic galena (PbS) and hydrophilic pyrite (FeS2) surfaces, a single, mono-, and multilayer water adsorptions on the PbS and FeS2(100) surfaces have been simulated by means of density functional theory. The calculated results show that the water molecule adsorption on the hydrophobic PbS surface is via a hydrogen bond between the S and H atom and on the hydrophilic FeS2 surface is mainly via the interaction between surface Fe and the water O atom. On the galena surface, the hydrogen bond effect of multilayer water weakens the S···H bond interaction and leads to the galena surface being hydrophobic. For the pyrite surface, the hydrogen bond effect of the multilayer water enhances the activity of the O 2p orbital and favors the interaction of the O 2p and Fe 3d eg orbital, which results in the pyrite surface being hydrophilic and undergoing a greater relaxation. These variations may have a great influence on the subsequent interfacial reactions on the galena and pyrite surfaces.