Investigation of Proton Diffusion Coefficient for PbO2 Prepared from Intermediate Oxides

Abstract

Lead dioxide was extracted from used batteries, and used to synthesize the following intermediate oxides by heating at different temperatures: Pb₁₂O₁₉, Pb₁₂O₁₇, and Pb₃O₄. 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 Pb₁₂O₁₉ only had a pattern similar to that of the starting PbO₂ with α-PbO₂ and β-PbO₂ phases. The measurements of H⁺ proton diffusion coefficient (D_H+) of the different samples showed that the sample prepared from Pb₁₂O₁₉ had better electrochemical performances than the starting PbO₂. This kinetics reflects the proton insertion mechanism in PbO₂, i.e. the sample prepared from Pb₁₂O₁₉ has a large amount of structural water in OH^– hydroxyl form. This amount contributes more in the PbO₂ reduction mechanism. In addition, the D_H+ value of the sample prepared from Pb₁₂O₁₉ is significantly higher than that of starting PbO₂, 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.