Linking the Cu(II/I) potential to the onset of dynamic phenomena at corroding copper microelectrodes immersed in aqueous 0.5 M NaCl

Electrochemical studies have been conducted at copper microelectrodes (125, 50, and 25 μm in diameter) immersed in aqueous 0.5 M NaCl. Cyclic and linear sweep voltammetry were used to explore the corrosion of copper in chloride media. Cyclic voltammetry revealed the reversible Cu(I)/Cu(0) potential at approximately −0.11 V vs. SCE associated with the formation of a dense CuCl blocking layer (confirmed by in situ Raman and fluorescence measurements). Although continuous dissolution of Cu(I) occurs, only an increase in the driving potential into the region of the Cu(II)/Cu(I) potential at approximately +0.14 V vs. SCE started more rapid and stochastic dissolution/corrosion processes. The corrosion process is demonstrated to be linked to two distinct mechanisms based on (A) slow molecular dissolution and (B) fast colloidal dissolution. A polymer of intrinsic microporosity (PIM-EA-TB) is employed to suppress colloidal processes to reveal the underlying molecular processes. [Display omitted] •Copper microelectrodes mimic pore corrosion in model sea water.•Onset of stochastic corrosion phenomena are linked to Cu(II) formation.•Polymer of intrinsic microporosity allows to distinguish between molecular and colloidal corrosion mechanisms.