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 (Ov) enhance the mobility of surrounding oxygen ions mobility and promoted the conversion from lattice oxygen (Olat) 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.