Cyclic voltammetric behaviour and some surface characteristics of the lead electrode in aqueous NaCl solutions

Abstract

Linear sweep voltammograms of a lead anode were studied in aqueous 1.0–3.0 M NaCl solutions. The voltammograms exhibited one anodic peak current density ( j ap) caused by the anodic dissolution of lead and formation of a thin passivating PbCl 2 surface layer. It was found that j ap is proportional to c Nacl The potential E ap corresponding to ( j ap) shifted to more negative values with increase of c NACl indicating that the passivating layer is formed more readily. Intensive study of the electrochemical behaviour of the lead electrode in 3.0 M NaCl solutions was carried out by cyclic voltammetry. The cathodic half-cycle showed a cathodic peak current density ( j cp) corresponding to reduction of the PbCl 2 layer formed during the anodic half-cycle. Controlling the voltammetric conditions enabled the buildup of a relatively thick and porous PbCl 2 surface layer which resists rupture or breakdown. The PbCl 2 surface layers formed under various conditions were investigated using scanning electron microscopy and X-ray diffractometry. The morphology of the PbCl 2 layers formed showed a primitive dependence on the employed conditions. X-ray diffraction analysis of the electrode surface products proved that only PbCl 2 was formed and no other species could be detected.