Anodic Oxidation of Copper in Alkaline Solutions: I . Nucleation and Growth of Cupric Hydroxide Films

The anodic oxidation of copper in solution has been investigated by galvanostatic, potentiostatic, and voltammetric sweep techniques. The structure and composition of the films were determined by x‐ray and electron diffraction, and by scanning electron microscopy. forms in two layers: a base layer grown by a solid‐state mechanism and an upper layer of individual crystals nucleated and grown from solution. The size and number of upper layer crystals are dependent on electrode potential. More anodic potentials produce a large number of randomly deposited crystals, whereas less anodic potentials result in fewer, more highly developed crystals. Increased stirring results in a greater loss of material into solution, and in the extreme, nucleation and growth are completely prevented. For sufficiently low crystallization rates, produced galvanostatically, the thermodynamically stable phase,, is formed. At higher rates the formation of dominates. A nucleation and growth mechanism is given and discussed with reference to other metal systems.