Electrochemical investigation of the oxides formed at the surface of brass (Cu–10Zn) by a humid-air plasma treatment

Linear potential sweep voltammetry was used to characterize the metal oxides formed at the surface of brass (Cu–10Zn) foils exposed to a gliding-arc-humid-air plasma. This study confirmed the formation of copper and zinc oxides (i.e. Cu2O, CuO, and ZnO). The electrochemical reduction curves in aqueous solutions of the different brass samples showed that copper and zinc oxides were characterized by their cathodic peaks. The reduction potentials of the oxides varied with the exposure time to the plasma at fixed working conditions. The analysis of the voltammetry curves showed that the initial oxide layer was formed in majority by the precursor oxide CuxO (x>4) and Cu2O. The oxidation of Cu(I) oxide (CuxO and Cu2O) lead to the formation of CuO. When the CuO layer was extensively grown, the ZnO oxide began to grow. A mechanism was proposed for the reduction of thin films containing Cu2O, CuO and ZnO oxides formed at the surface of the sample.