PHOTOELECTROCHEMICAL STUDY OF PASSIVE LAYERS ON COPPER ELECTRODES IN SOME ALKALINE MEDIA

来源期刊：中国有色金属学报(英文版)1998年第2期

论文作者：A. Kamkin Zhou Guoding Xu Qunjie B. H. Loo

文章页码：304 - 309

Key words：copper electrode;　alkaline solutions;　passive layer;　photocurrent response;　cyclic voltammetry

Abstract: The electrochemical behavior of Cu electrodes in alkaline solutions with and without argon-gas purging was studied by cyclic voltammetry and the photocurrent response method. In Na₂SO₄ solution (pH 9.1), the electrode shows a p-type photoresponse initially, which changes to an n-type when pitting corrosion occurs, at potentials more positive than the critical breakdown potential. The cathodic photocurrent is much larger in stronger alkaline solutions, e. g.,0.1 mol/L KOH solution, reflecting a more porous structure of Cu₂O layer on the electrode surface in strong alkaline solutions. Additionally, the cathodic current is larger in deaerated solutions than that in non-deaerated solutions. While the initiation of CuO formation on the electrode may not be obvious on the current-voltage curve, it can be obtained from the photocurrent-voltage curve where it corresponds to the onset of the decrease in the photocurrent on the positive potential scan.