STUDY OF COPPER SULFIDE FILM FORMATION BY VOLTAMMETRY COMBINED WITH ELECTROCHEMICAL QUARTZ-CRYSTAL MICROGRAVIMETRY COULOMETRY AND OPTICAL SPECTROSCOPY/

This paper describes a study of copper sulfide film formation at coppe r anodes in sulfide-containing aqueous NaOH media. Voltammetry along w ith combined electrochemical quartz crystal microgravimetry (EQCM)/cou lometry showed the formation of an initial Cu2S (chalcocite) phase. Fu rther oxidation resulted in a nonstoichiometric overlayer culminating in a surface that was CuS (covellite) in composition. The EQCM data al so revealed incipient dissolution of the copper surface in the alkalin e sulfide media as Cu(I) species. Chemical sulfidization of the copper surface is also shown to be an important film formation pathway. Comp lementary spectroscopic data were obtained in situ by visible reflecta nce spectroscopy and laser Raman spectroscopy. Ex situ analysis of the copper sulfide layer composition by X-ray photoelectron spectroscopy is also presented.