Visible light for enhancing the reusability of MOF-derived FeO@MoS heterojunction in the rapid degradation of Cu-EDTA by activated peroxymonosulfate: Performance and mechanism.

The metal-organic framework derived (MOF-derived) FeO@MoS heterojunction was synthesized to accelerate the self-catalyzed degradation of Cu-EDTA in low-dose peroxymonosulfate (PMS, 0.5 mM). 94.5 % of 0.2 mM Cu-EDTA was degraded in 15 min in the MOF-derived FeO@MoS/PMS/Dark system, accompanied by 50.0 % of the initial total copper release. The self-catalyzed degradation of Cu-EDTA accounted for 35.99 % of its overall degradation within 15 min. The recycling experiments indicated that visible light greatly improved the reusability of MOF-derived FeO@MoS with an increase of 35.6 % in the Cu-EDTA degradation in the 5th cycle, which was attributed to the exclusive acceleration of the Fe(III)-Fe(II) cycle by photogenerated electrons accumulated on the conduction band of α-FeO. Meanwhile, the phase transition of MoS and the reduction-deposition of CuO enhanced the photocatalytic activity of the heterojunction. •OH was found to be the dominant reactive oxygen species (ROS) in the MOF-derived FeO@MoS/PMS system whether visible light was introduced or not. The DFT calculations revealed that the adsorption configuration of PMS on the heterojunction governed the types of ROS, while the transfer of photogenerated electrons in the type-II heterojunction regulated the yields of different ROS. This study provides a new approach for constructing an efficient, low-cost, and sustainable system for accelerating Cu-EDTA degradation in PMS using self-catalysis.