Revisiting the catalytic activity of a doped SrFeO3 for water pollutants removal: effect of light and temperature

A Sr0.85Ce0.15FeO3-δ perovskite-type mixed oxide was prepared by solution combustion synthesis from citric acid and carefully characterized for the structure by X-ray diffraction coupled with Rietveld analysis, for the microstructure/morphology by HRTEM and SEM, for texture by N2 uptake at low temperature, for surface charge by ζ potential measurements and for reactive species by Electron Paramagnetic Resonance (EPR). Photocatalytic activity was tested in the presence of simulated solar light towards Orange II and Rhodamine B as model pollutants. Despite this compound is known as photocatalyst, a good reactivity was evidenced in the 55–80 °C temperature range without light irradiation, indicating that it can work as well in the dark after thermal-activation. Therefore, experimental data obtained in this work suggest to carefully reconsidering the role of this mixed oxide as photocatalyst. EPR spin-trapping tests allowed to deepen the aspects related to reactive species generated by Sr0.85Ce0.15FeO3-δ, revealing that the temperature increase promotes hydroxyl radicals and singlet oxygen production. Furthermore, an interesting selectivity towards the degradation of different dyes was found.