In Situ Growth of Bi2S3/Bi2MoO6/WO3 Double Type-Ii Heterojunction for Enhanced Cr(VI) Reduction: Experimental and DFT Study

Tungsten trioxide (WO3) is a widely used semiconductor photocatalyst for environmental photocatalytic remediation, but its practical application is severely limited by inherent drawbacks: wide band gap, poor visible light response, and rapid recombination of photogenerated electron-hole pairs. In this study, a Bi2S3/Bi2MoO6/WO3 double type-II heterojunction heterojunction photocatalytic film was rationally fabricated through a sequential hydrothermal-solvothermal-in-situ growth strategy. Bi2S3 quantum dots were uniformly loaded on the Bi2MoO6/WO3 hierarchical structure, forming a ternary heterojunction with tight interfacial contact and efficient charge transfer channels. The photoelectrochemical and photocatalytic performance of the as-prepared material was optimized by tuning the in-situ growth time of Bi2S3. The optimal BS/BMO/WO3(1 h) sample has an extended light absorption range up to 700 nm, a high transient photocurrent density of 46 µA·cm− 2, and effectively improved separation and transport efficiency of photogenerated carriers. Under simulated sunlight irradiation at pH = 3, this sample achieved a 74.4