Voltammetric study of electro-reduction of tetraamminepalladium(II) onto gold electrode

The work presents studies of the mechanism and kinetics of tetraamminepalladium(II) electro-reduction in ammonia – chloride solutions at pH = 9.5. The studies were preceded by the thermodynamic analysis of the electrolyte. The electrolyte stability was determined by UV–Vis absorbance measurements. Electrochemical examinations were performed by applying cyclic voltammetry (CV) combined with electrochemical quartz crystal microbalance (EQCM). The M/z values determined during electrogravimetric measurements indicate that reduction process of [Pd(NH3)4]2+ occurs in one step due to 2-electrons irreversible reduction reaction. Deposition of Pd takes place only in the overpotential deposition range. The examined reactions are diffusion controlled. Diffusion coefficient of [Pd(NH3)4]2+ participating in particular reactions was determined with the use of Berzins–Delahay equation.