High resolution Cu 2p spectra of Cp samples are shown in Fig. 3-B. In
the Cu 2p3/2 spectra, a peak at 932.5 eV is attributed to CuI in a sulfide
lattice [11,27,36]. The portion of surface CuII oxide and hydroxide
(bands near 934 eV and 935 eV) was small and no shake-up satellites
were observed. The XPS spectra of copper fromCp samples conditioned
at oxidative and reductive potentials were almost identical in peak
shape.