Breaking the barrier of Algal resistance: FeMoS₂/g-C₃N₄/Vis system for enhanced peroxydisulfate activation and Chlorella vulgaris inactivation

In this study, iron-doped molybdenum disulfide (FeMoS 2 ) was hydrothermally synthesized and subsequently coupled with calcined graphitic carbon nitride (g-C 3 N 4 ) to construct a heterojunction . Comprehensive characterization confirmed the stable crystalline structure of the composites and the formation of robust interfacial coupling, which facilitated efficient photogenerated charge separation. Furthermore, UV-Vis diffuse reflectance spectroscopy revealed a significant extension of the visible-light absorption edge compared to pristine FeMoS 2 , with the bandgap narrowing to 1.99 eV. Under optimized conditions (0.6 g/L catalyst dosage, 1.0 mM peroxydisulfate (PDS), pH 6), the FeMoS 2 /g-C 3 N 4 /PDS system achieved 88 % Chlorella vulgaris inactivation in 60 min under visible light, retaining more than 60 % efficiency after five cycles. Mechanistic investigations revealed that superoxide radicals (·O 2 - ) and photogenerated holes (h + ) synergistically inactivated Chlorella via reactive oxygen species (ROS)-induced membrane peroxidation and antioxidant system disruption. Algal physiological assays and microscopic imaging further corroborated that photocatalytically generated ROS compromised cellular membrane integrity and induced chloroplast degradation.