A STUDY OF COPPER ELECTRODE BEHAVIOR IN ALKALINE-SOLUTIONS CONTAININGBENZOTRIAZOLE-TYPE INHIBITORS BY THE PHOTOCURRENT RESPONSE METHOD ANDINTENSITY-MODULATED PHOTOCURRENT SPECTROSCOPY

The electrochemical behavior of copper electrodes in alkaline solution s containing benzotriazole, 6-tolytriazole and 1-(2,3-dicarboxypropyl) -benzotriazole was studied by the photocurrent response method and the intensity modulated photocurrent spectroscopy. The photocurrent obser ved from a Cu electrode in 0.1 M NaOH solution where the electrode sur face was covered with Cu2O was the result of the recombination of the photoexcited electrons through the photoreduction of the Cu+ ions, whi ch was then followed by a dark oxidation. In the case where both Cu2O and CuO were present on the electrode surface, the photocurrent was at tributed to the photoreduction of CuO as well as the recombination pro cess mentioned above. In solutions containing a corrosion inhibitor, t he formation of a thin Cu2O film strongly bonded to the upper layer of the adsorbed inhibitor occurred at potentials up to 0.5 V more negati ve than that in the absence of an inhibitor. These Cu2O underlayers we re probably intrinsic semiconductors. It was observed that the efficie ncy of an inhibitor on the copper corrosion correlated with its abilit y in stabilizing the Cu2O underlayer as well as its influence on the p hotocurrent response.