Cu adsorption on pyrite (1 0 0): Ab initio and spectroscopic studies

Surface optimised S 2p photoelectron spectra show that both surface S2− monomers and (S-S)2− dimers are present at pyrite (1 0 0) fracture surfaces. In order to determine which sulfur species are involved in Cu adsorption, fresh pyrite surfaces were exposed to Cu2+ in solution. The S 2p spectra suggest that both types of S surface species are involved in the mechanism of Cu adsorption (activation). Ab initio density functional theory was used to model Cu adsorbed onto pyrite (1 0 0) to support the interpretation of the spectroscopy. Mulliken population analysis confirms the charge distribution suggested by the core line shifts as observed in the photoelectron spectra. The ab initio calculations were consistent with a two-coordinate bond between Cu(I), a surface S monomer and a surface S dimer.