Design of S-scheme Fe3S4/Mn3O4 magnetic nanocomposites as photo-Fenton-like catalysts for efficient pollutant degradation

Abstract

The growing prevalence of organic contaminants in aquatic environments, particularly persistent and non-chromophoric compounds, poses significant environmental and regulatory challenges due to their resistance to conventional water treatment methods. In this work, we present the synthesis of a novel magnetic Fe₃S₄/Mn₃O₄ composite via a one-step hydrothermal process, engineered to enhance photocatalytic degradation efficiency under visible light irradiation. This strategy offers a sustainable and eco-friendly approach to addressing the critical need for robust, reusable, and low-leaching catalysts capable of degrading both dye-based and non-dye organic pollutants. Photocatalytic performance evaluation revealed that the Fe₃S₄/Mn₃O₄ composite achieved over 97.5 % degradation of methylene blue (MB) within 45 min at near-neutral pH, with high rate constant. Furthermore, the composite exhibited superior activity toward the recalcitrant, colorless pollutant Trichlorophenol (TCP), demonstrating degradation efficiencies much higher than those of Fe₃S₄ and Mn₃O₄, respectively. Incorporation of Mn₃O₄ was also found to significantly suppress sulphur leaching, thereby enhancing the material's environmental stability. Reactive species trapping experiments identified photogenerated holes (h⁺), superoxide radicals (^•O₂⁻), and hydroxyl radicals (^•OH) as the principal active species contributing to the degradation process.