3D MoS₂/MgIn₂S₄ Nanoflower Heterojunctions for Photoreduction of Cr(VI): Mechanism, Influence, and Toxicity Evaluation

Designing an efficient hole–electron separation method is essential to improving the photocatalytic efficiency of photocatalysts. Herein, we constructed a 3D MoS 2 /MgIn 2 S 4 S-scheme heterojunction material using a solvothermal method. The built-in electric field formed by the interaction between MoS 2 and MgIn 2 S 4 promoted the separation of electrons and holes, significantly improving the photocatalytic activity of 3D MoS 2 /MgIn 2 S 4 . The 3% MoS 2 /MgIn 2 S 4 composite photocatalyst successfully achieved a 100% reduction of Cr(VI) within 90 min and demonstrated good hydrogen production efficiency without using a sacrificial agent. Theoretical calculations confirmed the formation of S-scheme heterojunctions. Malondialdehyde and dehydrogenase tests showed that the Cr(VI) solution after reduction was not harmful to plant growth. Furthermore, we systematically investigated the effects of different Cr(VI) concentrations, catalyst dosages, ions, pH values, and organic acids on photocatalytic efficiency. The design of the S-scheme heterojunction photocatalysts provided a promising strategy for the photoreduction of Cr(VI).