2008 Volume 57 Issue 7 Pages 327-333
A new voltammetric method using a strongly alkaline electrolyte (6 M KOH+1 M LiOH) as the supporting electrolyte was applied for simultaneous determination of copper oxides and sulfides. It was found that the reduction peak of Cu2S was well separated from those of copper oxides and appeared at a somewhat higher potential than that of Cu2O. Unlike in the case of the reduction of CuO, CuS was reduced in a stepwise manner. The amounts of Cu2S formed on Cu plates were determined by the LSV method and found to agree well with the values determined by ICP-OES. In the voltammetric measurement of a copper plate in 6 M KOH+1 M LiOH containing S2−, the existence of Cu2S could be confirmed by the emergence of its redox peak pair. The proposed voltammetric method enables the quantitative estimation of a Cu2S film of a few nm thickness formed on Cu. In addition, Cu9S5 could be detected by its reduction peak appearing at a potential slightly higher than Cu2S.