Cyclic voltammetry on lead electrodes in sulphuric acid solution

✍ Scribed by W. Visscher

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 366 KB
• Volume: 1
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/0378-7753(76)81003-8

✦ Synopsis

The oxidation of lead in 5 M H2SO4 was studied by cyclic voltammetry. When a potential scan is applied from --1.0 V to 2.6 V vs. R.H.E. the PbSOJPbO2 oxidation peak can be observed in the anodic voltammogram provided the scan rate is 0.16 mV/s or lower. When the potential scan is restricted to the potential range +0.6 V to +2.6 V the anodic voltammogram shows two peaks which were assigned to the formation of ~-PbO2 and /3-PbO 2 respectively. This ~-PbO2 is formed underneath the PbSO4 film. During the reverse sweep the main reduction peak at 1.65 V corresponds with the reduction of ~-PbO2 to PbSO4. ~-PbO2 is not reduced at a definite potential but it is reduced to n-PbO. PbSO4 with n increasing from the oxide-electrolyte interface towards the interior of the electrode and with more cathodic potential. At potentials below 0 V, the basic lead sulphates are reduced.

The effect of the addition of small amounts of H3PO 4 to the H~SO4 electrolyte during the potential scanning results in an increase of the a-PbO2 peak and a disappearance of the ~-PbO2 peak.