In-situ investigation of the semiconductive properties and protective role of Cu2O layer formed on copper in a borate buffer solution

The semiconductor properties and protective role of a single-component Cu2O layer were studied using cyclic voltammetry, Mott–Schottky (MS) tests, electrochemical impedance spectroscopy (EIS), in-situ laser Raman spectroscopy, and electrochemical atomic force microscopy techniques (ECAFM). The results suggest that the single-component Cu2O layer exhibits p-type semiconductor properties. An interesting phenomenon was observed; the carrier concentration, and the diffusivity of the Cu+ vacancies increased progressively as the oxide layer formation potential increased. The oxide layer was composed of granular cuprous oxide; relatively large Cu2O particles were formed on the surface under − 120 mV (Ag/AgCl) and − 60 mV (Ag/AgCl). At a film formation potential of − 120 mV (Ag/AgCl), the thickness of the oxide layer (Cu2O) was approximately 6.046 nm, while it was 0.5594 nm at 0 mV (Ag/AgCl). The Cu2O layer formed at a lower potential offers superior stability and protection.