X-ray absorption spectroscopy of electrochemically oxidized Cu exposed to Na 2S

Abstract

Copper surfaces have been investigated by X-ray absorption spectroscopy after electrochemical oxidation and subsequent exposure to sulfide solution. Oxide surface layers on bulk copper surfaces were electrochemically grown in an aqueous NaOH solution at two different potentials and the resulting chemical composition was investigated using X-ray absorption spectroscopy. At both potentials the resulting surfaces consisted largely of Cu 2O. At the more strongly oxidizing potential, an admixture of Cu 2+-containing phases – mostly Cu(OH) 2 – was detected. Sulfide exposure of both surfaces was found to completely reduce the surface from Cu 2+ to Cu 1+ and resulted in the formation of Cu 2S with an admixture of Cu 2O.