Biomimetic preparation of MoS2-Fe3O4 MNPs as heterogeneous catalysts for the degradation of methylene blue

In this work, we reported the preparation of MoS2-based Fe3O4 magnetic composites (MoS2-Fe3O4 MNPs) through the biomimetic strategy, which relied on the self-polymerization of dopamine under alkaline aqueous solution. The utilization of MoS2-Fe3O4 MNPs as catalysts for Fenton reaction to degrade organic dyes was also examined in details. A number of experimental parameters, including concentrations of H2O2, dosages of MoS2-Fe3O4 MNPs and pH values on the degradation efficiencies were evaluated. The mechanism for catalytic degradation of methylene blue through Fenton reaction was illustrated by electron spin resonance (ESR) measurement and results indicated that the generation of center dot OH and center dot O-2(-) is the major reason for the degradation reaction. The results from recycle experiments suggest that catalysts possess good reusability. We demonstrated that Fe3O4 MNPs would be well dispersed on the surface of MoS2 sheets relied on the linkage by polydopamine (PDA), which prevented the aggregation of Fe3O4 MNPs and thus maintained high efficiency. Furthermore, we proved that the catalysts could also have high removal efficiency under low catalyst dosage and H2O2 concentration. In conclusion, we believed the MoS2-Fe3O4 MNPs could be successfully fabricated via the biomimetic strategy and should be promising candidates for environmental treatment. The biomimetic method should be also expanded for fabrication of other functional composites owing to the universal adhesion of PDA.