Ferric iron reduction reaction electro-Fenton with gas diffusion device: A novel strategy for improvement of comprehensive efficiency in electro-Fenton.

Applying the optimal 2-electron oxygen reduction reaction potential in electro-Fenton (2eORR-EF) for degradation has become a common strategy because of the highest HO generation rate in such condition. However, in 2eORR-EF system, the Fe(III) ions crystallize on the surface of cathode and form a layer of film according to SEM, XPS, XRD and Mössbauer spectrum resulting in poor reaction rate of EF. Hence, we propose FRR-EF, which is operated by applying the optimal potential of ferric iron reduction reaction (FRR) rather than that of 2eORR on cathode for EF. Gas diffusion device was also carried out to ensure the HO generation rate. In this novel strategy, only - 0.1 V was applied on cathode. High HO production rate (0.021 ± 0.002 mmol L min cm), and slow Fe(II) consumption rate (0.03 min) were achieved. The EIS result showed that at this potential, the formation of the Fe film was effectively alleviated, thus prolonging the degradation life of the cathode. This new strategy can balance both 2eORR and FRR, thus improving the comprehensive efficiency of EF, which provides essential references to the EF not only in potential operation but also in the design of reaction device.