The Cu∕CuF[sub 2] Couple in Anhydrous Hydrogen Fluoride

The electrochemical behavior of a Cu electrode was investigated in basic, anhydrous . Anodization of Cu established the couple. Micropolarization and bias tests indicated that this couple was reversible, and its potential vs. an H2 electrode in the same solution agreed well with that predicted from thermodynamic data. Thus the couple is suitable for use as a reference electrode in basic . The formation of a relatively thick, insoluble anodic film at a copper electrode was demonstrated by cyclic voltammetry and chronopotentiometry. Anodic‐cathodic cycling of an electrode gave rise to significant roughening of the electrode surface as shown by i‐E curves, E‐t curves, and differential capacitance measurements on cycled electrodes. X‐ray analysis of the anodic film confirmed the presence of crystalline copper fluoride. The formation of appears to proceed via dissolution of Cu to form Cu2+ ions, followed by precipitation of the on the electrode surface. The polarization behavior of Cu electrodes in anhydrous solution containing added showed that anodic film formation can be approximated by Tafel lines with an apparent exchange current density of about . Properties of the anodic film of are quite similar to those observed for noncontinuous anodic films formed in aqueous solutions.