Electrochemical Ozone Generation on a Nanocomposite SnO2 Electrode

A nanocomposite SnO2 electrode was prepared and its performance on electrochemical ozone synthesis was studied. The factors affecting ozone production and its current efficiency, such as current density, temperature, pH, supporting electrolyte and liquid flow, were investigated. The formation of hydroxyl radical was detected using trapping protocol and was compared with ozone generation. The results indicate that the ozone production increases with current density, and an optimum current density of 5 mA cm(-2) is obtained for the current efficiency of ozone generation. Lower temperature, lower pH and higher liquid flow favor ozone production as well as its current efficiency. As a supporting electrolyte, Na2SO4 appears to be more suitable than NaClO4, NaNO3 and NaCl for ozone generation on the nanocomposite SnO2 electrode. An optimum electrolyte concentration of Na2SO4 is observed to be 0.25 M, and a little bit of KPF6 addition (0.01 - 0.05 M) has an obviously positive effect on ozone generation. Current density and solution pH have a coincident effect on ozone and hydroxyl radical generation, while temperature has an inconsistent effect on ozone and hydroxyl radical generation and KPF6 addition has no effect on hydroxyl radical generation on the nanocomposite SnO2 electrode. The morphology and structure of the nanocomposite SnO2 electrode before and after accelerated life test were characterized by SEM and XRD analysis. It is suggested that the deactivation of nanocomposite SnO2 electrode is caused by the destruction of SnO2 coating film and the growth of TiO2 between Ti-base and SnO2 coating film.