2D–2D g-C3N4/WS2 Z-scheme heterojunction: Comparison of the photocatalytic degradation of tetracycline and sulfamethoxazole

In recent years, 2D–2D layered heterojunctions have emerged as promising photocatalytic platforms for the sustainable destruction of refractory pollutants because of their distinct advantages. Herein, we have rationally synthesized an organic–inorganic g-C3N4/WS2 heterojunction, with intimate interfacial contact, via a facile hydrothermal-driven self-assembling approach. Systematic investigations involving electrochemical impedance spectroscopy measurements and Mott–Schottky analysis reveal that the internal electric field between g-C3N4 and WS2 induces a Z-scheme charge transfer mechanism. Under visible light irradiation, the optimized photocatalyst exhibits high degradation efficiency towards two broad-spectrum antibiotics, i.e., tetracycline (TC) (89 %) and sulfamethoxazole (SMX) (97 %), with apparent reaction rate constants several folds higher than that of bulk g-C3N4 and pristine WS2 nanosheets. Further, the g-C3N4/WS2 photocatalyst shows favorable recycling stability by retaining over 80 % of the initial activity after four continuous photocatalytic runs. Additionally, the impacts of different reaction variables are explored and the probable routes of photocatalytic dissociation of TC and SMX by g-C3N4/WS2 are proposed. The present findings not only validate the feasibility of g-C3N4/WS2 to eliminate consumer-derived micropollutants from the aqueous phase without creating secondary pollutants but also provide important insights for designing highly efficient 2D material-based heterojunction photocatalysts for decentralized wastewater treatment.