Fundamental Studies on Electrochemical Deposition of Lead from Lead Oxide in 2:1 Urea/Choline Chloride Ionic Liquids

Ionic liquids have shown to be environmental friendly electrolytes that are suitable for electrodeposition of metals. In this work, lead oxide (PbO) was dissolved in 2:1 mole ratio of urea/choline chloride (Urea/ChCl) eutectic mixture at different temperatures (343 to 363 K). Electrochemical measurement confirms that the reduction peak potential for Pb (II) to Pb at –0.43 V vs. Ag reference electrode. The reduction of Pb (II) to Pb is characterized as an irreversible process and controlled by diffusion of electroactive species in the electrolyte. The value of diffusion coefficient varies between 1.09 × 10 −8 and 1.42 × 10 −7 cm 2 /s at temperatures from 343 to 363 K, respectively. The activation energy of the reaction is 124.7 kJ/mol. Three-dimensional (3D) instantaneous nucleation and growth process is predominant at reduction potentials studied. The SEM images of the electrodeposits obtained at –0.5 to –1.1 V show dendritic-type morphology of Pb particles. The XRD and EDS analysis confirm that the electrodeposits are consisted of high-pure Pb metal.