Self-cycled photocatalytic Fenton system and rapid degradation of organic pollutants over magnetic 3D MnS nanosheet/iron-nickel foam

The photocatalysis self-Fenton systems by coupling photocatalysis and Fenton technology overcome the limitations of conventional Fenton reactions by in-situ generation and activation of H2O2. While a considerable amount of iron sludge is still produced. In this study, we develop a novel self-cycled photocatalytic Fenton process for the degradation of organic pollutants via an iron-nickel foam-supported MnS nanosheet (MnS/INF). Without the external addition of both H2O2 and ferrous ions, MnS/INF 3D Z-scheme heterojunction exhibited an extremely high H2O2 production rate of 25.4 mM h-1 g-1 under visible light irradiation, which is 2119 times than those reported photocatalysis self-Fenton system in the literature. The photogenerated electrons of MnS/INF can participate in the Fe2+/Fe3+ cycle process to promote H2O2 activation, significantly enhancing the catalytic performance owing to the formation of a 3D Z-scheme heterojunction. DFT calculations indicate that MnS/INF can lower the energy barrier of *OOH formation and result in an enhanced photocatalytic activity of H2O2 production. Magnetic MnS/INF was easily recycled, remained very stable, and mitigated the extra undesirable Fe-containing sludge and only little iron sludge (0.43 mmol/L) is produced after nine cycles of reuse. Furthermore, a large (100 cm2) MnS/INF was used for an unassisted solar-driven in situ photocatalytic H2O2 production and rapid degradation of RhB with requirements for only water, oxygen and sunlight. In addition, MnS/INF also exhibited good performance in real wastewater containing fluoronitrobenzene from a factory (initial COD 2310 mg/L) and wastewater from sewage treatment station (initial COD 106 mg/L). This work may provide leverage to minimize iron sludge from the Fenton reaction's source.