Leveraging Ag₆Si₂O₇/WS₂ heterostructures to advance photocatalytic processes for environmental remediation via S-scheme

The rational design of semiconductor photocatalysts offers a promising strategy for addressing environmental pollution through solar-driven degradation of organic contaminants. In this study, a novel Ag₆Si₂O₇/WS₂ heterojunction photocatalyst was synthesized via a hydrothermal method and engineered to operate via an S-scheme mechanism. Comprehensive physicochemical characterization revealed abundant oxygen vacancies, improved visible-light absorption, and efficient charge separation driven by an internal electric field at the heterointerface. Among the various compositions, the AgWS-15% composite exhibited outstanding photocatalytic degradation efficiencies of 97.70% for Rhodamine B (RhB) and 98.11% for Methylene Blue (MB) within 40 min, achieving rate constants that were over 25 times higher than those of the pristine components. Trapping experiments and ESR analysis confirmed the dominant role of superoxide radicals (•O₂^-) and photogenerated holes (h⁺) in the degradation process. Furthermore, LC-MSanalysis identified key intermediates, supporting the proposed degradation pathway. To reinforce the experimental observations, density functional theory (DFT) simulations were conducted, revealing favorable band alignment, enhanced optical absorption, and interfacial electronic coupling in the AgWS-15% heterostructure. The combined experimental and theoretical results highlight the potential of Ag₆Si₂O₇/WS₂ composites as efficient and stable photocatalysts for visible-light-driven environmental remediation.