VOLTAMMETRY AND XPS ANALYSIS OF A CHALCOPYRITE CUFES2 ELECTRODE

A chalcopyrite CuFeS2 electrode obtained from the ''El Teniente'' mine (Chile) has been studied by cyclic voltammetry (CV) in a borax alkali ne solution at pH 9.2 and by X-ray photoelectron spectroscopy (XPS) be fore and after the electrochemical treatment at oxidation and reductio n potentials. The voltagram shows two peaks in the positive sweep dire ction which can be assigned to an oxidation process at the electrode s urface that involve the formation of Fe2O3 and CuO giving rise to an i rregular surface layer of the electrode with islands of different chem ical composition. The XPS results confirm the formation of Fe2O3 and C uO at the electrode surface and their stability against decomposition at reduction potential. In addition, the formation of FEOOH, CuFeO and CuS species at the electrode surface can be deduced by XPS as well as a covering of the whole electrode surface by species due to carbon-ox ygen groups. (C) 1998 Elsevier Science B.V. All rights reserved.