The effect of the surface state on the electrochemical behaviour of copper electrodes

Abstract

All investigated treatments of copper electrodes, which include mechanical (grinding and polishing with abrasives of different grain size: 210, 85, 75 and 42 μm), chemical (polishing, etching and shine-etching) and electrochemical (polishing), lead to an increase both of the anodic (copper dissolution) and of the cathodic (hydrogen evolution and oxygen reduction) polarization. This effect may be explained by the combined action of several types of factors. (1) Change in the real surface area of the examined electrode. This is the only factor in the case of mechanical treatment and an important factor for all other cases. (2) Formation of oxygen layers on the surface, an important factor in all types of chemical and electrochemical treatment. (3) Removal of the deformed layer composed upon mechanical polishing. This factor fully affects the electrochemically polished samples, partially the chemically polished one and does not affect the other types of chemical treatment. (4) These data correlate well with, and confirm, the concept about the higher electrochemical homogeneity of the electrochemically polished surface in comparison to the mechanically polished one. Our investigations show that a correct choice of the nature and sequence of the preliminary treatment of copper electrode surface makes it possible to impart on it the desired surface and electrochemical properties.