Electrocrystallization of copper sulphide (CU2S) on copper

The anodic formation of copper sulphide on copper was studied at various pH and sulphide concentrations. The kinetics and mechanism of film formation were elucidated by cyclic voltammetry and transient techniques. It was found that the film grows by a nucleation and growth mechanism controlled by localized hemispherical diffusion which, at long times, turns into linear diffusion due to overlapping of the diffusion zones of neighbouring centres. The analysis indicates that the number of active centres available for the nuclei formation is finite. The kinetic parameters for the nucleation have been interpreted according to the classical and atomistic models of nucleation. It is also shown that potentiostatic and galvanostatic techniques give comparable results.