Enhanced photo-Fenton performance using binary iron-based FeIn2S4@FeWO4 composite catalyst: Pollutants degradation in wastewater

As known, the photo-Fenton process is an efficient technology for the degradation of pollutants in wastewater. Herein, a type-II heterojunction composite was constructed by combining FeWO 4 with a nanorod morphology and microspherical FeIn 2 S 4 via hydrothermal synthesis method and applied in photo-Fenton catalytic degradation experiments for pollutants removal. It is found that, under light irradiation, the as-prepared FeIn 2 S 4 @FeWO 4 –0.25 (FIS@FWO-0.25) composite exhibits superior catalytic performance, achieving for tetracyclines (TC) a removal rate of 95.8% within 60 min, which is significantly outperformed the individual components: FeWO 4 (70.1%) and FeIn 2 S 4 (62%). The reaction rate constant over FeIn 2 S 4 @FeWO 4 –0.25 is 2.9 times that of FeWO₄ and 3.3 times of FeIn₂S₄, indicating a substantial enhancement in catalytic efficiency. Moreover, FIS@FWO-0.25 also exhibits high degradation efficiency for other types of antibiotics such as ciprofloxacin (CIP), norfloxacin (NOR), sulfamethoxazole (SMZ), and dyes like Rhodamine B (RhB). From a structural perspective, the spherical architecture of FeIn 2 S 4 provides an ideal substrate for the growth of FeWO 4 nanorods. This distinctive morphological combination effectively increases the specific surface area of the material, thus providing more active sites for the photo-Fenton reaction. More critically, the successful construction of the type-II electron transfer mechanism significantly accelerates the separation efficiency of photogenerated electron-hole pairs. The improved separation efficiency of photogenerated charge carriers, in turn, promotes the generation of a greater quantity of reactive oxygen species, which constitutes the core mechanism responsible for the significant enhancement in antibiotics degradation efficiency. The FeIn 2 S 4 @FeWO 4 –0.25 composite demonstrated good adaptability under various environmental conditions and maintained high catalytic activity after multiple reuse cycles, showcasing excellent structural stability and performance durability. Within this photo-Fenton system, photogenerated holes (h + ) served as the primary active species participating in the degradation reaction. Meanwhile, hydroxyl radicals (•OH), singlet oxygen ( 1 O 2 ), and superoxide radicals (•O 2 − ) also played synergistic roles. The concerted action of these multiple reactive species collectively promotes the efficient decomposition of pollutants molecules. • FeWO 4 @FeIn 2 S 4 type-II heterojunction was prepared by hydrothermal method. • The built-in electric field facilitates the type-II photogenerated carrier transfer mechanism. • FeIn 2 S 4 @FeWO 4 showed superior photo-Fenton activity for TC degradation. • Photogenerated holes and multiple radicals synergistically drove the degradation process.