Electrochemistry of Pb(II)/Pb during preparation of lead wires from PbO in choline chloride—urea deep eutectic solvent

Abstract

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 Ea 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 µ.m in length and 2.5 µ.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.