Cathodic reduction of copper oxides

The determination of oxide thickness via cathodic reduction was developed in 1936. It is a simple laboratory practice that has the sensitivity and capability to analyze total oxide thickness of both cuprous and cupric oxides within the same run. Unfortunately, contradictory results and misidentification of oxide layers on the copper surface have caused ambiguity in the interpretation of many published results, leading to its incorrect use in industrial applications. This review surveys experimental parameters used by the authors, such as electrolyte composition and concentration, current density, current efficiency, sample history, interfacial impedance, crystalline orientation, and concentration of depolarizer on the cathodic reduction of copper oxides. Ultimately, the goal of the review is to propose solutions by which more precise measurement and correct identification of oxide layers could be derived from this type of experiment.