Nanoflower-like Co₃S₄/FeOOH heterostructure enables efficient norfloxacin degradation via synergistic radical-non-radical PMS activation

Abstract

This study developed a monolithic Co₃S₄/FeOOH nanoflower(NF)-like catalyst through impregnation-boiling and mild hydrothermal methods (120 °C, 3 h), overcoming the drawbacks of both conventional ex-situ loading techniques (uneven distribution) and powdered catalysts (difficult separation). The in-situ grown nanoflower-like Co₃S₄/FeOOH composite on NF demonstrated superior peroxymonosulfate (PMS) activation, achieving 87.74% norfloxacin (NOR) removal under optimized conditions (1 cm² catalyst loading with 0.2 g CoCl₂·6H₂O precursor, 0.3 g/L PMS dose, initial pH 6.3), representing around 11-fold and 1.8-fold higher degradation rates than single-component FeOOH/NF and Co₃S₄/NF, respectively. Mechanistic insights of such performance enhancement revealed by electrochemical analysis and Density functional theory (DFT) calculations. Quenching experiments and Electron paramagnetic resonance (EPR) analysis confirmed the coexistence of synergistic pathways involving radical species (SO₄^•−) and non-radical processes (¹O₂ and electron transfer). The Co₃S₄/FeOOH/NF & PMS system retains 84.73% NOR degradation after 3 cycles with stable morphology, while achieving broad-spectrum antibiotic removal (83.69%–99.88%). Fluorescence analysis confirms almost complete mineralization of recalcitrant humic substances from the real hospital wastewater within 40 min.

Graphical abstract

Keywords

Co₃S₄/FeOOH / Nickel foam / In-situ growth / PMS activation / NOR degradation

Highlight

	● In-situ nanoflower Co3S4/FeOOH/NF by mild impregnation-hydrothermal method.
	● Superior PMS activation with 11-fold activity enhancement.
	● Enhanced e- transfer at Co3S4/FeOOH/NF vs monometallic components.
	● NOR was degraded through both free-radical and non-radical pathways.
	● Excellent cyclability, low ecotoxicity and high real-wastewater efficacy.

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