CHARACTERIZATION OF COPPER OXIDATION BY LINEAR POTENTIAL SWEEP VOLTAMMETRY AND UV-VISIBLE-NIR DIFFUSE REFLECTANCE SPECTROSCOPY

The aim of this study was to characterize the compounds grown on copper during oxidation at low temperature (T < 573 K) in air by electrochemical and optical methods. The following oxides have been characterized: a precursor Cu(x)O of mixed valency character, a non stoichiometric cuprous oxide, CuO and its precursor. The mechanism of reduction has been established for layers containing CuO and a non stoichiometric copper(I) oxide. CuO is reduced before cuprous oxide. In complicated cases, it is impossible to draw conclusions from the characteristics of the electrochemical reduction (the first step of CuO reduction and the reduction of Cu(I) species specific of the non-stoichiometry are observed at the same potential). Nevertheless, the association of a non-destructive technique such as diffuse reflectance spectroscopy and electrochemical methods allows identification of the different species present in corrosion layers on copper surfaces.