A novel bifunctional cathode for the generation and activation of H2O2 in electro-Fenton: Characteristics and mechanism

External addition of Fe2+ is commonly required for the sake of activating H2O2 in electro-Fenton, which limits the reaction continuity and causes the potential secondary pollution. Herein, a novel bifunctional cathode (rGO/ MIL-88A/CF) was fabricated for achieving the in-situ H2O2 generation and activation simultaneously. The rotating disc electrode (RDE) test showed that the average electron transfer number was about 2.01, indicating that selective two-electron reduction of oxygen molecule (2e- ORR) occurred on the as-prepared cathode. The quenching experiments and EPR tests proved that the oxygen-containing reactive species such as OH center dot and O2 center dot- could be efficiently generated on rGO/MIL-88A/CF cathode, which contributed to the pollutant degradation. The obtained rGO/MIL-88A/CF cathode not only obtained the improvement of its charge transfer rate owing to the modification by the reduced graphene (rGO), but also acted as a stable activator for the electro-generated H2O2 without additional reagents. Moreover, rGO/MIL-88A/CF cathode effectively facilitated the circulation of Fe2+/ Fe3+ through cathodic reduction, which consequently enhanced the performance of the electro-Fenton. Our current investigation presented a feasible example of a novel bifunctional cathode applied in electro-Fenton towards efficient pollutant removal without exogenous H2O2 activator.

Automated summary

A novel bifunctional cathode (rGO/MIL-88A/CF) was successfully fabricated for in-situ H2O2 generation and activation. The cathode exhibited high electron transferability and ability to generate reactive species, contributing to efficient pollutant degradation. Moreover, the cathode acted as a stable activator without the need for additional reagents.