X-ray absorption spectroscopy of electrochemically oxidized Cu exposed to Na2S

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 Cu2O. At the more strongly oxidizing potential, an admixture of Cu2+-containing phases – mostly Cu(OH)2 – was detected. Sulfide exposure of both surfaces was found to completely reduce the surface from Cu2+ to Cu1+ and resulted in the formation of Cu2S with an admixture of Cu2O.

► X-ray absorbtion spectroscopy on electrochemically oxidized Cu exposed to sulfide solution.
► After electrochemical oxidation the outermost layer of our samples consists mostly of Cu(OH)2.
► Sample surfaces were chemically converted into Cu2S upon exposure to Na2S solutions.