Electrochemical control of gas-phase oxidation and reduction of copper as probed by surface-enhanced Raman spectroscopy

The presence or absence of copper surface oxidation in air is shown to be readily controllable by aqueous solution rinsing. The presence of a Cu2O film is detected from the 625/525 cm(-1) oxide vibrational features obtained by surface- enhanced Raman scattering. Flushing with acidic solutions removes the Cu2O film to yield a reduced surface, whereas rinsing with aerated neutral or alkaline media immediately regenerates the oxide. The findings are entirely compatible with the occurrence of electrochemical half-reaction pathways for surface oxidation and reduction. (C) 1999 The Electrochemical Society. S1099-0062(98)09-002-6. All rights reserved.