The electrochemical behaviour of copper in aerated 1 mol·dm-3 NaCl at room temperature: Pt. 2

Uniform corrosion will be an important process in determining the lifetime of a copper nuclear fuel waste container. We need to know the mechanism of the corrosion reaction if we are to make reliable predictions about the long-term corrosion behaviour. This series of reports summarizes the results of an electrochemical investigation of the corrosion of copper in aerated 1 mol·dm-3 NaCl at room temperature. In part 2 we discuss the cathodic reduction of oxygen on a copper rotating disc electrode. The anodic dissolution of copper and the behaviour under freely corroding conditions are considered in Parts 1 and 3, respectively. The mechanism of the oxygen reduction reaction has been studied over a wide range of applied potentials. At potentials close to the corrosion potential, the mechanism is complicated and not fully understood. It is possible that in this potential region, oxygen is reduced to peroxide. At more negative applied potentials, between -0.50 and -0.90 Vsce, the predominant process is the 4-electron reduction of oxygen to hydroxide. In this potential region, the rate is controlled jointly by the interfacial reaction and the rate of supply of oxygen to the electrode surface. At an applied potential of about -1.0 Vsce, the rate of reduction is almost totally controlled by the rate of transport of oxygen. Values for the kinetic parameters for the 4-electron reaction have been determined. In addition, the diffusion coefficient of oxygen was found to be 1.73 ± 0.05 x 10-5 cm2·s-1. These data, along with the results on the anodic dissolution of copper, will be used to explain the behaviour of copper under freely corroding conditions