Pb electrodeposition from PbO in the urea/1-ethyl-3-methylimidazolium chloride at room temperature

Abstract

In this study, we dissolved PbO in a new electrolyte urea/1-ethyl-3-methylimidazolium chloride (EMIC) and electrochemically extracted Pb. The electrochemical behavior of lead was investigated using chronoamperometric and cyclic voltammetric techniques. The cyclic voltammograms illustrated that lead reduction is quasi-reversible and follows a single-step, two-electron transfer process. The chronoamperometric experiments showed that lead reduction in the PbO–urea/EMIC system follows a 3D instantaneous nucleation and a diffusion-controlled growth at 353 K. The diffusion coefficient was 1.67 × 10⁻⁸ cm² s⁻¹. The effect of temperature on the electrochemical behavior of lead was investigated. Results showed that electrode reaction becomes more reversible as temperature increases from 343 to 373 K. The diffusion coefficients increase with increasing temperature and obey the Arrhenius' law. The activation energy is estimated to be 38 kJ mol⁻¹. Electrodeposition experiments were conducted on tungsten substrates at different negative potentials and various temperatures. Scanning electron microscopy (SEM) images of electrodeposits showed that the Pb particles became smaller and are more densely distributed at more negative potentials and higher temperatures. The obtained electrodeposits were metallic lead, as verified by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS).