S‐Scheme SnS ₂ /WO _3‐x Heterojunction for Efficient and Stable Photocatalytic Degradation of Dichlorvos

ABSTRACT

The extensive use of organophosphorus pesticides has caused serious residue problems, posing potential risks to food safety, aquatic environments, and ecosystem health. Therefore, developing photocatalytic materials with efficient charge separation and stable catalytic activity is important for the green degradation of pesticide residues. Herein, an S‐scheme SnS ₂ /WO _3‐x heterojunction photocatalytic system was rationally constructed for dichlorvos (DDVP) degradation. SnS ₂ (NS) and WO _3‐x (WO) achieved DDVP degradation efficiencies of 60.3% and 58.8%, respectively, within 120 min, whereas NS/WO nanocomposites showed markedly enhanced activity. Among them, 70‐NS/WO, with an NS feeding ratio of 70%, exhibited the optimal degradation efficiency of 75.8%. After five consecutive cycles, corresponding to 600 min of total irradiation, 70‐NS/WO retained 92.3% of its initial activity, indicating excellent cycling stability. X‐ray photoelectron spectroscopy (XPS) analysis and theoretical calculations support the proposed S‐scheme charge‐transfer pathway at the NS/WO interface. This heterojunction promotes directional carrier migration and efficient separation under the built‐in electric field, suppresses electron‐hole recombination, and preserves strong redox capability, thereby enhancing DDVP degradation. This work provides a strategy for constructing S‐scheme photocatalysts based on defective tungsten oxide and metal sulfides, offering a promising platform for sustainable remediation of organophosphorus pesticide contamination.