Electrochemical Behavior of Lead in Choline Chloride–Glycerol Deep Eutectic Solvent

Abstract

The electrochemical behavior of a solution containing 5 mmolal Pb(II) in a choline chloride–glycerol medium (molar ratio 1:2) was investigated at a glassy carbon (GC) electrode at 100 ± 5 °C. Electrochemical and physicochemical studies were carried out using techniques such as cyclic voltammetry, UV–Visible spectroscopy, chronoamperometry, chronopotentiometry, as well as scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS). The results indicate that the electrodeposition of Pb(II) on GC is characterized by a quasi-reversible process, controlled by the diffusion of electroactive species in the electrolyte. The electrodeposition of Pb(II) follows an instantaneous three-dimensional nucleation and growth mechanism (3D instantaneous, 3DI), with a diffusion coefficient estimated at 1.96 × 10⁻⁶ cm²·s⁻¹. SEM micrographs reveal a highly branched three-dimensional deposit morphology, consisting of a network of nanosheets or intertwined branches with a cauliflower-like structure. EDS analyses confirm that these deposits are composed of high-purity metallic lead.