Investigation of Proton Diffusion Coefficient for PbO2 Prepared from Intermediate Oxides

• Published in: Russian journal of electrochemistry 2019-07, Vol.55 (7), p.643-650
• Main Authors: Rahmani, L., Fitas, R., Messai, A., Ayesh, A. I.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Differential thermal analysis; Differential thermogravimetric analysis; Diffusion coefficient; Dioxides; Electrochemistry; Lead oxides; Oxidation; Physical Chemistry; Protons; Reduction; Sulfuric acid; Thermogravimetry; X-ray diffraction
• ISSN: 1023-1935; 1608-3342
• DOI: 10.1134/S1023193519070103

Lead dioxide was extracted from used batteries, and used to synthesize the following intermediate oxides by heating at different temperatures: Pb 12 O 19 , Pb 12 O 17 , and Pb 3 O 4 . Each of the prepared intermediate oxide was subject to sulfuric acid with 1.28 g cm –3 . X-ray diffraction (XRD) results showed that the sample prepared from Pb 12 O 19 only had a pattern similar to that of the starting PbO 2 with α-PbO 2 and β-PbO 2 phases. The measurements of H + proton diffusion coefficient (D H+ ) of the different samples showed that the sample prepared from Pb 12 O 19 had better electrochemical performances than the starting PbO 2 . This kinetics reflects the proton insertion mechanism in PbO 2 , i.e. the sample prepared from Pb 12 O 19 has a large amount of structural water in OH – hydroxyl form. This amount contributes more in the PbO 2 reduction mechanism. In addition, the D H+ value of the sample prepared from Pb 12 O 19 is significantly higher than that of starting PbO 2 , which confirms this hypothesis. X-ray diffraction analysis, thermogravimetric and differential thermogravimetry analysis, and cyclic voltammetry reduction at different scanning rates were used to investigate the samples. This work contributes to environment preservation by recycling of used lead dioxide and reduction of the hazard of its disposal on water.