Cobalt electrodeposition on polycrystalline palladium. Influence of temperature on kinetic parameters

Cobalt electrodeposition on polycrystalline palladium was studied at different temperatures using potentiostatic and voltammetric techniques. Temperature effect on kinetics parameters, diffusion coefficient, and charge transfer coefficient was analyzed. The values of nucleation rate and rate constant of the proton reduction reaction (kPR) increased with the temperature increment and the applied overpotential. The number of active nucleation sites was slightly affected with temperature increase. At higher temperatures, the larger kPR values suggested the proton reduction process is favored. The temperature effect on the values of the transfer coefficient was analyzed and a decrease in its value with the temperature increase was observed. From a Conway plot, it was observed that entropy change is the main factor that controls the kinetics of the reaction in this system.