Novel Fe2O3@MoS2 nanofibers with significantly enhanced peroxymonosulfate activation by piezoelectric effect for organic pollutant degradation

Background

α-Fe₂O₃ is a promising activator of peroxymonosulfate (PMS) to degrade organic pollutants but is heavily limited by the inevitably sluggish conversion rate of Fe³⁺ to Fe²⁺.

Methods

This work presents a type II heterojunction of MoS₂ nanosheets decorated on Fe₂O₃ (Fe₂O₃@MoS₂, FM) nanofibers for significantly enhanced activation of PMS to effectively degrade various contaminants. FM fibers were facilely prepared by hydrothermal growth of MoS₂ nanosheets with 1T and 2H mixed phases on hollow electrospun Fe₂O₃ nanofibers.

Significant findings

The MoS₂ nanosheets are separated with each other with intact heterojunction interface with Fe₂O₃ nanofibers. By applying an sonication (US), the transfers of piezoelectric e^- and Mo⁴⁺ from MoS₂ to Fe₂O₃ are significantly accelerated by the piezoelectric field inside the MoS₂ nanosheets. As a result, a large amount of Fe²⁺ is produced as activator of PMS to achieve a superior degradation performance of RhB solution by FM with a kinetic constant of 1.2639 min^-1. The scavenger degradation and electron spin resonance (ESR) experiments demonstrate that ¹O₂, ·O₂^-, e^-, SO₄·^- and ·OH contribute to the degradation process under the PMS/US. Meanwhile, the PMS is demonstrated to be the source to generate the reactive species mainly activated via Fe²⁺ reduced by Mo⁴⁺ and piezoelectric e^-. The aggregation of the nanostructures can be effectively avoided due to the unique fibrous structures.