Tuning the Initial Electronucleation Mechanism of Palladium on Glassy Carbon Electrode

Electrochemical metal nucleation is the method for the formation of metal nanoparticles on the electrode surface. Studying the early stage of electronucleation is simpler than other methods as the driving force for nucleation is achieved by changing deposition potentials and concentration of metal ions. In this work, the potential step electrochemical deposition of palladium was studied from its chloride solution at room temperature on glassy carbon electrode surface. The nucleation mechanism was studied by analysis of the resulting current transients. Accordingly, the initial electro-nucleation mechanism of palladium nanoparticles was found to be varying depending on deposition conditions such as deposition potential and palladium concentration. It can be changed from 3D instantaneous (for all deposition potentials studied and in higher electrolytic concentration) to 3D progressive nucleation mechanism (for lower deposition potential and lower electrolytic concentration). In addition, the nucleation rate for each deposition potential as well as the concentration has been determined. The nucleation rate in this research is used to calculate the nuclei density and found to decrease from more negative deposition potential to more positive deposition potential in agreement with the observed shift in electronucleation mechanism.