Dual modified MoS2/SnS2 photocatalyst with Z-scheme heterojunction and vacancies defects to achieve a superior performance in Cr (VI) reduction and dyes degradation

Efficient and sustainable wastewater treatment requires highly active and controllable photocatalysts. Defect engineering and heterojunction are two promising approaches in enhancing the activity of photocatalysts, but the synergy effect between them has rarely been studied. In this paper, we announced an intelligible hydrothermal method to craft a direct Z-scheme heterostructure photocatalyst by growing MoS2 on the surface of vacancy-rich SnS2. The unique MoS2/SnS2 photocatalyst with heterojunction and sulfur vacancies possessed a boosting performance in hexavalent chromium (Cr (VI)) photoreduction and organic dyes photodegrading. The optimal MoS2/SnS2 photocatalyst with Mo: Sn = 7.5% achieved the best photocatalytic performance with the efficiency of 99.9% (Cr (VI)) and 96.5%(MB), and the constant values were up to 0.020 min−1 and 0.079 min−1 individually, which is 10 and 7.9 times that of pure SnS2. The Z-scheme charge transfer route was verified by the free radical and holes trapping test and the shifted peaks of X-ray Photoelectron Spectroscopy (XPS) spectra. The improvement can be related to the synergistic effect highly suppressed the reunion of photogenerated electrons and holes, and significantly raised the utilization rate of visible light. Therefore, this novel system greatly improves the photocatalytic performance of pure SnS2. This discovery comes up with a new strategy for photocatalysts properties upgrading, and opens up a new window to realize the efficient removal of Cr (VI) and organic dyes in industrial effluent.