XPS STUDIES OF ANODIC SURFACE-FILMS ON COPPER ELECTRODES

X-ray photoelectron spectroscopy was employed to study surface films generated by anodic electrochemical oxidation of copper in Na2S04 solutions at pH = 12. A simple and efficient, low-cost transfer system is described which allows electrochemical manipulation and transfer of specimens into the vacuum analysis chamber under an inert atmosphere. Copper covered with oxygen and oxide species was found to be hydrophilic. Sputter depth profiles revealed the nature and extent of the surface films withdrawn from solution. An adherent liquid electrolyte film of ca. 0.3 jam thickness dried out upon emersion of the electrode and formed an approximately 30A thick overlayer of Na2S04, NaOH, and H20 on underlying electrochemically formed anodic layers of the order of 40A. Two oxidation states, Cu20 and Cu(OH)2, could be well resolved, each occurring at their respective equilibrium potential. copyright. © 1990, The Electrochemical Society, Inc. All rights reserved.