Efficient Activation of Peroxymonosulfate for Degradation of Rhodamine B by Anchoring CoFe₂O₄ on MoS₂ Nanoflower-Modified Biochar

In this study, CoFe₂O₄ anchored by MoS₂ modified biochar (CoFe₂O₄@MoS₂-BC) was synthesized using a hydrothermal approach and utilized to activate peroxymonosulfate (PMS) to degrade rhodamine B (RhB). The effects of pH value, catalyst and PMS dosage, RhB concentration, and coexisting compounds were systematically investigated. Within 7 min, CoFe₂O₄@MoS₂-BC achieved a removal rate of 99.63% for 100 mg·L^-1 RhB. The outstanding stability and environmental compatibility of CoFe₂O₄@MoS₂-BC was verified by cycling and metal ion leaching experiments. The contribution of ¹O₂, SO₄^•-, ^•OH, and ^•O₂^- in the degradation procedure was revealed by quenching experiments, among which ¹O₂ was the predominant active species. Electrochemical characterization indicated that CoFe₂O₄@MoS₂-BC exhibited enhanced current density, redox activity, and superior electron transfer capability. Comprehensive characterization analysis and experimental data revealed that the high efficiency of CoFe₂O₄@MoS₂-BC was attributed to Co²⁺/Co³⁺, Fe²⁺/Fe³⁺, and Mo⁴⁺/Mo⁶⁺ redox cycling on the CoFe₂O₄@MoS₂-BC surface. The cycles of Co²⁺/Co³⁺ and Fe²⁺/Fe³⁺ were enhanced by Mo, while unsaturated S increased the reactivity of Mo, thereby accelerating the redox of metal ions; oxygen vacancies (O_v) enhance the mobility of surrounding oxygen ions mobility and promoted the conversion from lattice oxygen (O_lat) to reactive oxygen species (O*), thereby activating PMS effectively. This research is expected to provide innovative insights that will inform the design and development of excellent activity and stability of heterogeneous metal-based catalysts.