Voltammetric investigations of copper processes in the presence of oxygen

The redox processes of copper ions were studied by alternating current (ac) voltammetry and cyclic voltammetry in 0.5 M NaCl and NaClO4 solutions. The studies were performed at different pH values in the presence of atmospheric oxygen or by the addition of H2O2 to the process. In the case of copper ions in NaCl solution both in the presence of atmospheric oxygen and added H2O2, a catalytic current was observed. With cyclic voltammetry the current was in the cathodic direction in spite of having an anodic sweep. The key factor is the presence of chloride ions as in the NaClO4 solution; the observed catalytic current peaks are much smaller. The mechanism for the observed redox processes of copper is proposed.