A kinetic study on the electrodeposition of cadmium with the presence of organic agents in sulfate solutions

The electrodeposition of cadmium is studied by electrochemical techniques with the presence of the organic agents. The cyclic voltammetry results clearly show that the electrodeposition of cadmium is a diffusion-controlled process associated with a typical nucleation process. With addition of the thiourea, 3-Picolin and benzyl alcohol organic agents simultaneously in sulfate solution, the redox potential of cadmium is shifted to more negative potentials. In this case, the current transients reveal an instantaneous nucleation with a typical three-dimensional (3D) growth mechanism, while it shows progressive nucleation mechanism without the ternary-species organic agents. In addition, the number of nucleation sites is increased with overpotential and cadmium concentration, so the deposition rate is increased. However, the microstructure of the Cd electrodeposits is changed dramatically with the presence of the ternary-species organic agents. In these conditions, the fine-grained deposits with a large number of equally sized hexagonal grains are observed.