Piezoelectric field-promoted heterogeneous sono-Fenton performance of MoS2/α-Fe2O3 heterojunction structure

The limited Fe-III/Fe-II cycle in iron-based heterogeneous catalysts is one of the main technical obstacles to the heterogeneous Fenton-like application. This work demonstrates the catalytic performance improvement of MoS2/alpha-Fe2O3 heterojunction in the Fenton-like reaction, specifically in the sono-Fenton reaction. The rate constant of degrading Acid Orange 7 (AO7) with MoS2/alpha-Fe2O3 heterojunction presents ca. 26.0 and 14.8 times higher than those with pristine alpha-Fe2O3 and MoS2 catalysts, respectively. Experiments with the addition of various scavengers demonstrated that O-1(2), radical O-center dot(2)-, and radical (OH)-O-center dot are the dominant, sub-dominant, and least-dominant ROS in the reaction, respectively. The reaction mechanism is further proposed on account of the characterization and experimental results. MoS2 participates in the Fenton-like reaction as a catalyst; besides, the Fesingle bondS bond observed at the interface accelerates the FeIII/FeII cycle by enhancing the electron transfer from Mo to Fe. Notably, ultrasonic irradiation evokes a piezoelectric potential on the surface of MoS2, which reduces the interfacial barrier height of MoS2/alpha-Fe2O3 heterojunction, accelerating the electron transfer through the Fesingle bondS bond and thus dramatically boosting the sono-Fenton activity. These findings could provide an alternative strategy to enhance the iron-based heterogeneous Fenton catalytic reactivity.