Electrochemical Behavior of PdCl2 in 1-Ethyl-3-Methylimidazolium Chloride Ionic Liquid at Pt-Ir Electrode

Electrodeposition of palladium in ionic liquids has not been actively investigated. Herein, the electrochemistry of PdCl2 for electrodeposition of palladium in 1-Ethyl-3-Methylimidazolium Chloride ([EMIM][Cl]) ionic liquid (IL) was studied at a Pt-Ir working electrode. A rotating disc was applied to allow a better understanding of the reaction kinetics. A range of techniques, such as cyclic voltammetry (CV) and current-time transient, were used to elucidate the electrochemistry of palladium of PdCl2 in [EMIM][Cl] IL under both stationary and rotating conditions. Two cathodic waves and two anodic waves were observed in CV. We propose that both of the cathodic peaks, which are separated by the surface alteration of the electrode during the cathodic scan, are produced by the electroreduction of PdCl4 (2-) to palladium, with their characteristics of mixed kinetics and mass transfer controlled, respectively. Regarding the nucleation of palladium on Pt-Ir electrode, a 3D, instantaneous nucleation mechanism was proved under quiescent conditions. The nucleation of Pd at rotating disc electrode(RDE) was fmodeled, and it was found that RDE promote instantaneous nucleation of Pd.