Electrochemistry of Pb(II)/Pb during Preparation of Lead Wires from PbO in Choline Chloride-Urea Deep Eutectic Solvent

The electrochemistry of Pb(II)/Pb on a stainless steel electrode during the preparation of lead wires from PbO in choline chloride (ChCl)-urea deep eutectic solvent (DES) was investigated by means of cyclic voltammetry, cathodic polarization and chronoamperometry. The experimental results indicated that the reduction of Pb(II) to Pb is a quasi-reversible process controlled by diffusion at temperature varying from 323 to 343 K, and the corresponding apparent activation energy E-a is 52.37 kJ mol(-1). The analysis of chronoamperometry measurements suggested that the initial stage of nucleation of lead on stainless steel electrode is a three-dimensional instantaneous nucleation under diffusion control. The effects of reaction time and temperature on the morphology of lead deposits are also examined. The lead wires obtained at 343 K for 120 min have a mean particle size of 30 mu m in length and 2.5 mu m in diameter. Based on experimental evidence, the deposition mechanism of sub-micrometer lead wires on stainless steel substrate is proposed by diffusion controlled growth mechanism.