XPS AND ISS STUDIES ON THE INTERACTION OF H2S WITH POLYCRYSTALLINE CU, CU2O AND CUO SURFACES

The first steps of H2S adsorption have been studied on polycrystalline copper samples, which are more relevant to industrial copper samples than to single-crystal surfaces. The tools for characterization are ultrahigh vacuum spectroscopic methods, such as x-ray photoelectron and ion scattering spectroscopies. The H2S adsorption on metallic copper and on the corresponding Cu2O and CuO oxides is dissociative and highly dependent on the chemical nature of the exposed surface rather than on the temperature, from room temperature up to 623 K. In our conditions, Cu degrees sulphidation deals with the top Cu degrees layer whereas two to three oxide surface monolayers are modified at H2S saturation. The results on oxides are interpreted by an oxygen/sulphur replacement mechanism following the dissociative adsorption. Contaminated copper surfaces by phenanthrene or H2O treatments are hardly sulphided. As far as surface reactivity is concerned, the adsorbed sulphide species have been shown to be quite strongly bound to the different surface states tested in this work: only oxidative treatments induce desorbing products at 623 K.