Abstract: The electrochemical behavior of 10％Ni-90％Cu, 30％Ni-70％Cu, 50％Ni -50％Cu,5.1％Co-94.9％Cu, 9.7％Co-90.3％Cu, 15％Co-85％Cu, 25％Co-75％Cu an d 40％Co-60％Cu alloys electrodes in a borax buffer solution(pH 8.5) was studie d by cyclic voltammetry, AC impedance spectroscopy and photocurrent response met hod. The copper-nickel and copper-cobalt electrodes all show p-type photoresp onses. The photoresponses of the copper-nickel electrodes come from Cu2O while those of the copper-cobalt electrodes are caused by Cu2O and cobalt oxides. iph ,max of 10 ％Ni-90 ％Cu, 30 ％Ni-70 ％Cu and 5.1 ％Co-94.9 ％Cu alloy electro des is larger than that of pure copper electrode. However, iph,max of 50％Ni-50 ％Cu, 15％Co-85％Cu,25％Co-75％Cu and 40％Co-60％Cu alloy electrodes is small er than that of pure copper electrode because there are nickel and cobalt oxides on the greater part of the surface of those electrodes. φv of the copper-nick el electrodes is more negative than that of pure copper electrode while φv of t he copper-cobalt electrodes is almost equal to that of pure copper electrode. N iO results in a more stability of Cu2O layer on the copper-nickel electrodes su rface. The results from photoelectrochemical measurements favourably agree with those by AC impedance technique.

Key words: Cu-Ni alloy, Cu-Co alloy, Photoelectrochemistry, AC impedance, Corrosion