Enhanced simulated sunlight photocatalytic degradation over SnS/MgWO4 heterostructure through improved interfacial charge transfer

The contamination of water by organic dyes constitutes a major environmental challenge due to their good reusability under the tested conditions and toxicity. However, conventional photocatalysts exhibit low activity under simulated sunlight irradiation as well as rapid recombination of electron-hole pairs, limiting their effectiveness. In this work, an SnS/MgWO 4 heterostructure was designed to improve the photocatalytic performance under simulated sunlight irradiation. The material was successfully synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with EDX analysis (SEM-EDX), and diffuse UV–Visible spectroscopy (UV–Vis DRS), confirming the formation of a heterogeneous structure and enhanced visible-light absorption in the visible domain. The photocatalytic results show that the SnS/MgWO 4 composite has a significantly improved activity compared to the individual materials, with an apparent kinetic constant of 0.0264 min −1 , i.e., approximately 5 and 7 times higher than those of SnS (0.0069 min −1 ) and MgWO 4 (0.0036 min −1 ), respectively, yielding a degradation efficiency of 93% within 100 min under simulated sunlight, along with significant organic matter removal (as evidenced by COD reduction). This improvement is attributed to an efficient separation of the charges and to an optimized interfacial transfer. A mechanism based on a type of direct Z -scheme-type charge-transfer mechanism is proposed, involving the generation of reactive species such as • OH and O 2 •- . These results highlight the potential of this heterostructure for advanced applications in the treatment of water under simulated sunlight.