Determination of the Reduction Sequence in Cathodic Reduction of Duplex Copper Oxide Films Formed in Air
Sub-committee for Cathodic Reduction of Copper Oxi
Two plateaus are found in the potential vs. time curve when the duplex copper oxide film is cathodically reduced at a constant current density. However, there are contradictory mechanisms to assign these two plateaus. We must solve this problem to use catholic reduction for characterization of the duplex copper oxide film. The sub-committee for catholic reduction of copper oxide films constituted in 2002 and has been discussing the reduction sequence in catholic reduction of the duplex copper oxide film. We performed round robin experiments in three companies to determine the reduction sequence in the potential vs. time curve. In these experiments, the electrolyte was 0.1M KCl and reduction current density was 50μA/cm2. The specimens for catholic reduction were oxidized in a constant temperature humidity chamber at 60°C and 90%RH for 72h. The change in the XPS spectra of specimen surfaces revealed that cupric oxide was reduced in the first plateau, while cuprous oxide was reduced in the second plateau. Furthermore, we found that the cupric oxide was directly reduced to metallic copper by an experiment using the standard CuO/Cu specimen.