Influence of lead dioxide electrodes morphology on kinetics and current efficiency of oxygen-ozone evolution reactions

• Published in: Chemical papers Vol. 64; no. 6; pp. 749 - 757
• Main Authors: Rufino, Élen C. G., Santana, Mario H. P., De Faria, Luiz A., Da Silva, Leonardo M.
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Versita 2010; Versita
• Subjects: Biochemistry; Biotechnology; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; electrode kinetics; Industrial Chemistry/Chemical Engineering; interfacial capacitance; lead dioxide electrode; Materials Science; Medicinal Chemistry; morphology factor; Original Paper; ozone production; lead dioxide electrode; interfacial capacitance; morphology factor; electrode kinetics; ozone production
• ISSN: 0366-6352; 1336-9075; 1336-9075
• DOI: 10.2478/s11696-010-0062-2

Influence of electrode morphology on electrochemical properties of lead dioxide electrodes ( β -PbO 2 ) for oxygen-ozone evolution reactions in acid medium was investigated using scanning electronic microscopy (SEM), cyclic voltammetry (CV), polarization curves (PC), and determination of the current efficiency ( Φ ). Experimental findings revealed that application of high electrodeposition current densities furnishes more rough β -PbO 2 films. Surface characteristics were verified by SEM images and the analysis of interfacial pseudo-capacitances and morphology factor ( φ ). Kinetic study of the overall electrode process (O 2 + O 3 ) based on the analysis of the Tafel slope revealed that the electrode morphology and electrolyte composition considerably affect the electrode kinetics. In most cases, the existence of two Tafel slopes distributed in the low and high overpotential domains was observed. Abnormal Tafel slopes ( b ≠ 120 mV) obtained for the primary water discharge step during water electrolysis were interpreted considering the apparent charge transfer coefficient ( α apa ). Optimum conditions for the ozone production were obtained for the less rough β -PbO 2 electrode immersed in a sulfuric acid solution (1.0 mol dm −3 ) containing KPF 6 (30 × 10 −3 mol dm −3 ), where the current efficiency of 15 mass % for the ozone production was obtained.