A CORRELATION BETWEEN ELECTROCHEMICAL-BEHAVIOR, COMPOSITION AND SEMICONDUCTING PROPERTIES OF NATURALLY GROWN OXIDE-FILMS ON COPPER

Copper(I) oxide films formed under open-circuit potential in neutral aqueous solutions have been characterized, using coulometry, photocurrent spectroscopy and X-ray photo-electron spectroscopy (XPS). The reduction potential of the oxide layer was found to depend on the presence in the electrolyte of chloride ions, Cu(II) or Cu(I) ionic species or of a corrosion inhibitor. XPS analyses were performed on these oxide layers, and showed in some cases an evolution of the oxidation state of copper from +2 to +1 state throughout the film. Different conducting properties of the cuprous oxides could be demonstrated through photo-electrochemical measurements, and the formation of a duplex Cu2O layer with two semiconducting components of different stoichiometries was discussed.